Chameleon

.. image:: https://img.shields.io/pypi/pyversions/Chameleon
:alt: PyPI - Python Version
.. image:: https://img.shields.io/github/actions/workflow/status/malthe/chameleon/main.yml
:alt: GitHub Actions Workflow Status

Chameleon is an HTML/XML template engine for Python <http://www.python.org>_. It uses the page templates language.

You can use it in any Python application with just about any
version of Python (3.9+ and up, plus pypy 3 <http://pypy.org>_).

Visit the documentation <https://chameleon.readthedocs.io/en/latest/>_
for more information.

License and Copyright

This software is made available as-is under a BSD-like license [1]_
(see included copyright notice).

Notes

.. [1] This software is licensed under the Repoze <http://repoze.org/license.html>_ license.

Changes

4.6.0 (2024-12-31)

Improve startup time when no template is used.
Fix ast deprecation warnings up to Python 3.13.
(#430 <https://github.com/malthe/chameleon/issues/430>_)
Fix load_module deprecation warnings for Python >= 3.10.

4.5.4 (2024-04-08)

Fix an issue where $-sign interpolation escaping would not work
correctly when more than two such symbols appeared next to each
other.
(#422 <https://github.com/malthe/chameleon/issues/422>_)

4.5.3 (2024-04-05)

Minor optimization when rendering translations with a static
message id (don't need to test if it's non-empty).
Fix a bug where a macro could not be used correctly to render a
translation name.
(#419 <https://github.com/malthe/chameleon/issues/419>_)

4.5.2 (2024-01-29)

Fix a regression where a static symbol would not get correctly
imported.
(#414 <https://github.com/malthe/chameleon/issues/414>_)

4.5.1 (2024-01-28)

Add Python 3.13 classifier.
Fix a regression where default_extension was no longer permitted
as a positional argument to PageTemplateLoader.
(#411 <https://github.com/malthe/chameleon/issues/411>_)

4.5.0 (2024-01-18)

Chameleon now has type annotations!
The list of names previously disallowed for use as variables in
templates such as "int" and "float" has been trimmed significantly,
not because it's a good idea to use such names but because the list
of disallowed names was not exhaustive and complicated the compiler
code; and perhaps more importantly, the technical reason for
disallowing the names in the first place no longer applies.
Fix a regression where generated template code would suboptimal due
to incorrect handling of internal variables.
Always cook templates in debug mode, even when using
CHAMELEON_CACHE option to persist generated code on disk.
Parsing the AST back to Python code now uses the built-in
ast.unparse function. This change is not directly surfaced but
means that the unparsing code is now more correctly tracking changes
to the interpreter.
Drop support for platforms where AST nodes aren't weakref-capable
(e.g., older PyPy).

4.4.4 (2024-01-18)

Fix a PyPy compatibility issue having to do with determining the set
of versions when some packages (e.g. cffi) would not carry a
version.

4.4.3 (2023-12-30)

Remove zope.interface.
Fix an issue where auto_reload is enabled and a file is loaded
from a package that wasn't zip-compressed.
(#402 <https://github.com/malthe/chameleon/issues/402>_)

4.4.2 (2023-12-18)

Fix brown bag release.

4.4.1 (2023-12-18)

Fix brown bag release.

4.4.0 (2023-12-12)

Add optional parameter package_name which allows loading a
template relative to a package.
Drop support for Python 3.7.
Fix regression where Chameleon would not load templates correctly on
Windows.
Fix names of dependencies for importlib_resources and
importlib_metadata.
(#394 <https://github.com/malthe/chameleon/pull/394>_)

4.3.0 (2023-12-04)

Local variable scope is now iterable, completing dict interface.
(#390 <https://github.com/malthe/chameleon/pull/390>_)
Minor optimizations to rendering logic.
Implicit translation now provides the translation context, domain,
and target language to the translation function (if applicable). Previously,
the target language was provided, but this did not respect a change via
i18n:target.
(#369 <https://github.com/malthe/chameleon/issues/369>_)
Replace pkg_resources with newer and faster importlib.resources and
importlib.metadata. Just importing pkg_resources becomes slower and
slower the more packages are installed.

4.2.0 (2023-09-25)

An XML document provided as a string (i.e. decoded) now correctly
has its content encoding parsed.
Boolean attributes are now automatically configured for templates in
non-XML mode, presuming that we're being used to generate HTML.

This means that the same loading mechanism can be used for both XML-
and HTML-based templates.

4.1.0 (2023-08-29)

Boolean attributes (those configured using the optional
boolean_attributes parameter) now work with $-expression
interpolation.

Unlike content and regular attributes, a special check for a falsy
value is now done for boolean attributes, such that boolean logic
can be used for interpolation expressions (only a truthy value will
include the attribute).

This reverts a change in behavior introduced in 3.8.0.

Additionally, dynamic attributes now respect the boolean attributes
configuration as well.

4.0.1 (2023-06-19)

Fix format spec applying for f-strings.
(#376 <https://github.com/malthe/chameleon/issues/376>_)

4.0.0 (2023-03-06)

Drop support for Python 2.7, 3.5, 3.6.
Add support for set- and dict comprehensions
(#367 <https://github.com/malthe/chameleon/issues/367>_)
Remove the following functions resp. modules:
- .utils.text_()
- .utils.unescape()
- .compat

3.10.2 (2022-12-16)

Fix handling of eager compilation with subclassing (e.g. Pyramid integration).

3.10.1 (2022-05-17)

Fix str method of chameleon.exc.TemplateError
(#356 <https://github.com/malthe/chameleon/issues/356>_)

3.10.0 (2022-04-06)

Make scope class dict-like
(#305 <https://github.com/malthe/chameleon/issues/305>_)
Work in FIPS enabled environments
(#345 <https://github.com/malthe/chameleon/issues/345>_)
Fix tab handling issue
(#350 <https://github.com/malthe/chameleon/issues/350>_)

3.9.1 (2021-05-14)

Avoid various traceback reference cycles.

3.9.0 (2021-02-26)

Removed compatibility code for unsupported Python versions
Dropped support for obsolete Python 3.4
Fixed namespace handling when redefining a variable in the same tal:define
(#237 <https://github.com/malthe/chameleon/issues/237>_)
Fixed failure computing a template's digest if template.filename is None
(#254 <https://github.com/malthe/chameleon/issues/254>_)

3.8.1 (2020-07-06)

Added code optimization to reduce sequential appends of static text.
The default symbol in dynamic attributes is now
symbolic. Previously, it was assigned the string value of the
default attribute text. A similar change has been made for
switch/case expressions.
The built-in attrs dictionary of static element attributes now
correctly works with tal:define, etc.
Fix slice code generation compatibility issue on Python 3.9.

3.8.0 (2020-06-25)

Expose default marker as importable symbol
chameleon.tales.DEFAULT_MARKER.
Removed legacy flag literal_false. To get a similar behavior, use
boolean_attributes.

3.7.4 (2020-06-17)

Fix brown-bag release.

3.7.3 (2020-06-17)

Fix regression introduced in 3.6.2 where the default marker would
incorrectly change its value between templates, causing issues in
software which depends on the value being treated as a global
object.

3.7.2 (2020-05-31)

Allow setting a custom value representation function, allowing
custom formatting of variables during exception formatting.

3.7.1 (2020-05-10)

Fix compatibility issue with Python 3.9.

3.7.0 (2020-03-26)

Fixed garbage collection issue with variable scope objects (issue #301).
Fixed issue where setting a global variable would not be available
locally.
A RepeatDict no longer inherits from dict since it does not
actually provide that interface in a meaningful way.
Added feature gate enable_comment_interpolation which controls
whether expression interpolation is enabled inside HTML comments
(default is enabled).
Added support for Python 3.6+ f-strings (issue #294).

3.6.2 (2019-06-22)

Fix SyntaxWarnings in Python 3.8 resulting from comparing literals with 'is'.
See https://github.com/plone/Products.CMFPlone/issues/2890.

3.6.1 (2019-04-01)

Fix limited search expression for illegal double hyphens in HTML
comments to fix issue #289.

3.6 (2019-02-19)

Exclude RuntimeError (or RecursionError when available) from
exception wrapping.
Fix double dollar '$$' escaping such that a double dollar is always
resolved, either as an interpolation expression, or as an escape
where it is substituted by a single dollar symbol. This is now
consistent with Zope's handling of this character.

Backslash-escaping of dollar-based string interpolation is no longer
supported. The documentation has been updated to reflect this
change.

This fixes issue #283. Note that this reverses some of the changes
introduced to fix issue #265.
Drop support for Python 3.3.

3.5 (2018-10-17)

Add support for Python 3.8.
Add support for TAL attributes in an XML declaration tag. This fixes
issue #269.
Add support for custom exception handling for the tal:on-error
statement. There is now an option on_error_handler available
as a template configuration (issue #266).
Fix issue where double '$$' escaping would affect non-interpolation
expressions such as the bare '$$' (issue #265).
Fix an issue where backslash dollar escaping would leave the
backslash character still in place.

3.4 (2018-07-14)

Bugfixes:

Fix regression with translations in case of multiple nodes.

3.3 (2018-05-23)

Bugfixes:

Reset error token when rendering internal macro calls.
Fix edge case in exception handler causing recursion.
[MatthewWilkes]

3.2 (2017-10-06)

Features:

Add the automatic variable macroname that's bound to the name of
the executing macro. Fixes https://github.com/malthe/chameleon/issues/238
A tokenizer can now be configured on the template class. This is
useful in the case where the template file input is modified before
parsing (for example, where some tags are stripped away) such that
token positions need to be offset accordingly for error locations to
be rendered correctly.
Expression errors now display source marker (previously only
filename, line and column was shown).
No longer require Python source files to import modules.
[mrh1997]

Optimizations:

Exception tracking now defers metadata allocation to time of error.

3.1 (2017-02-21)

Features:

Add option restricted_namespace which controls whether to
restrict namespaces to those defined and used by the page template
language.
[hansroh]

Bugs:

Fixed attribute HTML entity escaping issue where an entity such as
& would be encoded twice.

Optimizations:

Simplify exception tracking, reducing bytecode size significantly.
Avoid checking if a static string is None during expression
interpolation.

3.0 (2016-12-07)

Bugs:

Fix issue on Python 2 where an exception was not cleared when using
the pipe operator and was thus accessible through sys.exc_info().
The "exists" expression no longer leaks error information.
Escape '$$' into '$' in both content and string expressions.
Fix use of macro definition inside translation block.

Improvements:

Allow unquoted attribute values.
Wrap attribute error thrown when trying to use a non-macro as a
macro as a RenderError to get proper error output.
Throw a parse error if '--' (double hyphen) appears in an XML
comment.
The i18n:target attribute now overrides a default
target_language variable and is passed to the translation
function.
Include filename in the on-disk cache module name. Previously,
only the SHA digest in hex representation would be used, making
it difficult to see where the module came from. This fixes issue
#132.
Add support for non-ascii attribute names.
[sank]

Compatibility:

Drop support for Python 2.6, 3.1, and 3.2.

2.25 (2016-09-24)

Add explicit support / testing for Python 3.5.
Add \r to negative regex matches to the chameleon parser, where \n is used but \r was missing.
Fixes a case, where the tag name was parsed into html\r instead of html.
Fixes: https://github.com/malthe/chameleon/issues/219

2.24 (2015-10-28)

Fixed Python 3.5 compatibility.
Fixed brown bag release.

2.23 (2015-10-26)

Added enable_data_attributes option that allows using HTML5 data
attributes as control attributes instead or in addition to XML
namespace attributes.

2.22 (2015-02-06)

Fix brown bag release.

2.21 (2015-02-06)

Added RenderError exception which indicates that an error
occurred during the evaluation of an expression.
Clean up TemplateError exception implementation.

2.20 (2015-01-12)

Pass search_path to template class when loaded using
TemplateLoader (or one of the derived classes).
[faassen]

2.19 (2015-01-06)

Fix logging deprecation.
Fix environment-based configuration logging error.

2.18 (2014-11-03)

Fix minor compilation error.

2.17 (2014-11-03)

Add support for i18n:context.
[wiggy]
Add missing 'parity' repeat property.
[voxspox]
Don't modify environment when getting variables from it.
[fschulze]

2.16 (2014-05-06)

If a repeat expression evaluates to None then it is now
equivalent to an empty set.

This changes a behavior introduced in 2.14.

This fixes issue #172.
Remove fossil test dependency on deprecated distribute.
Add explicit support / testing for Python 3.3 / 3.4.
Drop explicit support for Python 2.5 (out of maintenance, and no longer
supported by tox or Travis-CI).

2.15 (2014-03-11)

Add Support for Python 3.4's NameConstant.
[brakhane]

2.14 (2013-11-28)

Element repetition using the TAL namespace no longer includes
whitespace. This fixes issue #110.
Use absolute import for chameleon.interfaces module. This fixes
issue #161.

2.13-1 (2013-10-24)

Fixing brown bag release.

2.13 (2013-10-21)

Bugfixes:

The template cache mechanism now includes additional configuration
settings as part of the cache key such as strict and
trim_attribute_space.
[ossmkitty]
Fix cache issue where sometimes cached templates would not load
correctly.
[ossmkitty]
In debug-mode, correctly remove temporary files when the module
loader is garbage-collected (on __del__).
[graffic]
Fix error message when duplicate i18n:name directives are used in a
translation.
Using the three-argument form of getattr on a
chameleon.tal.RepeatDict no longer raises KeyError,
letting the default provided to getattr be used. This fixes
attempting to adapt a RepeatDict to a Zope interface under
PyPy.

2.12 (2013-03-26)

Changes:

When a tal:case condition succeeds, no other case now will.

Bugfixes:

Implicit translation now correctly extracts and normalizes complete
sentences, instead of words.
[witsch]
The default symbol in a tal:case condition now allows the
element only if no other case succeeds.

2.11 (2012-11-15)

Bugfixes:

An issue was resolved where a METAL statement was combined with a
tal:on-error handler.
Fix minor parser issue with incorrectly formatted processing
instructions.
Provide proper error handling for Python inline code blocks.

Features:

The simple translation function now supports the
translationstring interface.

Optimizations:

Minor optimization which correctly detects when an element has no
attributes.

2.10 (2012-10-12)

Deprecations:

The fast_translate function has been deprecated. Instead, the
default translation function is now always a function that simply
interpolates the mapping onto the message default or id.

The motivation is that since version 2.9, the context argument
is non-trivial: the econtext mapping is passed. This breaks an
expectation on the Zope platform that the context parameter is
the HTTP request. Previously, with Chameleon this parameter was
simply not provided and so that did not cause issues as such.
The ast24 module has been renamed to ast25. This should help
clear up any confusion that Chameleon 2.x might be support a Python
interpreter less than version 2.5 (it does not).

Features:

The ProxyExpr expression class (and hence the load:
expression type) is now a TALES-expression. In practical terms, this
means that the expression type (which computes a string result using
the standard "${...}" interpolation syntax and proxies the
result through a function) now supports fallback using the pipe
operator ("|"). This fixes issue #128.
An attempt to interpolate using the empty string as the expression
(i.e. ${}) now does nothing: the string ${} is simply output
as is.
Added support for adding, modifying, and removing attributes using a
dictionary expression in tal:attributes (analogous to Genshi's
py:attrs directive)::

In the example above, name is an identifier, while value and
attrs are Python expressions. However, attrs must evaluate
to a Python dictionary object (more concisely, the value must
implement the dictionary API-methods update() and items()).

Optimizations:

In order to cut down on the size of the compiled function objects,
some conversion and quoting statements have been put into
functions. In one measurement, the reduction was 35%. The benchmark
suite does not report of an increased render time (actually
slightly decreased).

Bugfixes:

An exception is now raised if a trivial string is passed for
metal:fill-slot. This fixes issue #89.
An empty string is now never translated. Not really a bug, but it's
been reported in as an issue (#92) because some translation
frameworks handle this case incorrectly.
The template module loader (file cache) now correctly encodes
generated template source code as UTF-8. This fixes issue #125.
Fixed issue where a closure might be reused unsafely in nested
template rendering.
Fixed markup class __repr__ method. This fixes issue #124.
Added missing return statement to fix printing the non-abbreviated
filename in case of an exception.
[tomo]

2.9.2 (2012-06-06)

Bugfixes:

Fixed a PyPy incompatibility.
Fixed issue #109 which caused testing failures on some platforms.

2.9.1 (2012-06-01)

Bugfixes:

Fixed issue #103. The tal:on-error statement now always adds an
explicit end-tag to the element, even with a substitution content of
nothing.
Fixed issue #113. The tal:on-error statement now works correctly
also for dynamic attributes. That is, the fallback tag now includes
only static attributes.
Fixed name error which prevented the benchmark from running
correctly.

Compatibility:

Fixed deprecation warning on Python 3 for zope interface implements
declaration. This fixes issue #116.

2.9.0 (2012-05-31)

Features:

The translation function now gets the econtext argument as the
value for context. Note that historically, this was usually an
HTTP request which might provide language negotiation data through a
dictionary interface.
[alvinyue]

Bugfixes:

Fixed import alias issue which would lead to a syntax error in
generated Python code. Fixes issue #114.

2.8.5 (2012-05-02)

Bugfixes:

Fixed minor installation issues on Python 2.5 and 3.
[ppaez]
Ensure output is unicode even when trivial (an empty string).

2.8.4 (2012-04-18)

Features:

In exception output, long filenames are now truncated to 60
characters of output, preventing line wrap which makes it difficult
to scan the exception output.

Bugfixes:

Include filename and location in exception output for exceptions
raised during compilation.
If a trivial translation substitution variable is given (i.e. an
empty string), simply ignore it. This fixes issue #106.

2.8.3 (2012-04-16)

Features:

Log template source on debug-level before cooking.
The target_language argument, if given, is now available as a
variable in templates.

2.8.2 (2012-03-30)

Features:

Temporary caches used in debug mode are cleaned up eagerly, rather
than waiting for process termination.
[mitchellrj]

Bugfixes:

The index, start and end methods on the TAL repeat object are
now callable. This fixes an incompatibility with ZPT.
The loader now correctly handles absolute paths on Windows.
[rdale]

2.8.1 (2012-03-29)

Features:

The exception formatter now lists errors in 'wrapping order'. This
means that the innermost, and presumably most relevant exception is
shown last.

Bugfixes:

The exception formatter now correctly recognizes nested errors and
does not rewrap the dynamically generated exception class.
The exception formatter now correctly sets the __module__
attribute to that of the original exception class.

2.8.0 (2012-02-29)

Features:

Added support for code blocks using the <?python ... ?> processing
instruction syntax.

The scope is name assignments is up until the nearest macro
definition, or the template itself if macros are not used.

Bugfixes:

Fall back to the exception class' __new__ method to safely
create an exception object that is not implemented in Python.
The exception formatter now keeps track of already formatted
exceptions, and ignores them from further output.

2.7.4 (2012-02-27)

The error handler now invokes the __init__ method of
BaseException instead of the possibly overridden method (which
may take required arguments). This fixes issue #97.
[j23d, malthe]

2.7.3 (2012-01-16)

Bugfixes:

The trim whitespace option now correctly trims actual whitespace to
a single character, appearing either to the left or to the right of
an element prefix or suffix string.

2.7.2 (2012-01-08)

Features:

Added option trim_attribute_space that decides whether attribute
whitespace is stripped (at most down to a single space). This option
exists to provide compatibility with the reference
implementation. Fixes issue #85.

Bugfixes:

Ignore unhashable builtins when generating a reverse builtin
map to quickly look up a builtin value.
[malthe]
Apply translation mapping even when a translation function is not
available. This fixes issue #83.
[malthe]
Fixed issue #80. The translation domain for a slot is defined by the
source document, i.e. the template providing the content for a slot
whether it be the default or provided through metal:fill-slot.
[jcbrand]
In certain circumstances, a Unicode non-breaking space character would cause
a define clause to fail to parse.

2.7.1 (2011-12-29)

Features:

Enable expression interpolation in CDATA.
The page template class now implements dictionary access to macros::

template[name]

This is a short-hand for::

template.macros[name]

Bugfixes:

An invalid define clause would be silently ignored; we now raise a
language error exception. This fixes issue #79.
Fixed regression where ${...} interpolation expressions could
not span multiple lines. This fixes issue #77.

2.7.0 (2011-12-13)

Features:

The load: expression now derives from the string expression such
that the ${...} operator can be used for expression
interpolation.
The load: expression now accepts asset specs; these are resolved
by the pkg_resources.resource_filename function::

:

An example from the test suite::

chameleon:tests/inputs/hello_world.pt

Bugfixes:

If an attribute name for translation was not a valid Python
identifier, the compiler would generate invalid code. This has been
fixed, and the compiler now also throws an exception if an attribute
specification contains a comma. (Note that the only valid separator
character is the semicolon, when specifying attributes for
translation via the i18n:translate statement). This addresses
issue #76.

2.6.2 (2011-12-08)

Bugfixes:

Fixed issue where tal:on-error would not respect
tal:omit-tag or namespace elements which are omitted by default
(such as <tal:block />).
Fixed issue where macros attribute would not be available on
file-based templates due to incorrect initialization.
The TryExcept and TryFinally AST nodes are not available on
Python 3.3. These have been aliased to Try. This fixes issue
#75.

Features:

The TAL repeat item now makes a security declaration that grants
access to unprotected subobjects on the Zope 2 platform::

allow_access_to_unprotected_subobjects = True

This is required for legacy compatibility and does not affect other
environments.
The template object now has a method write(body) which
explicitly decodes and cooks a string input.
Added configuration option loader_class which sets the class
used to create the template loader object.

The class (essentially a callable) is created at template
construction time.

2.6.1 (2011-11-30)

Bugfixes:

Decode HTML entities in expression interpolation strings. This fixes
issue #74.
Allow xml and xmlns attributes on TAL, I18N and METAL
namespace elements. This fixes issue #73.

2.6.0 (2011-11-24)

Features:

Added support for implicit translation:

The implicit_i18n_translate option enables implicit translation
of text. The implicit_i18n_attributes enables implicit
translation of attributes. The latter must be a set and for an
attribute to be implicitly translated, its lowercase string value
must be included in the set.
Added option strict (enabled by default) which decides whether
expressions are required to be valid at compile time. That is, if
not set, an exception is only raised for an invalid expression at
evaluation time.
An expression error now results in an exception only if the
expression is attempted evaluated during a rendering.
Added a configuration option prepend_relative_search_path which
decides whether the path relative to a file-based template is
prepended to the load search path. The default is True.
Added a configuration option search_path to the file-based
template class, which adds additional paths to the template load
instance bound to the load: expression. The option takes a
string path or an iterable yielding string paths. The default value
is the empty set.

Bugfixes:

Exception instances now support pickle/unpickle.
An attributes in i18n:attributes no longer needs to match an
existing or dynamic attribute in order to appear in the
element. This fixes issue #66.

2.5.3 (2011-10-23)

Bugfixes:

Fixed an issue where a nested macro slot definition would fail even
though there existed a parent macro definition. This fixes issue
#69.

2.5.2 (2011-10-12)

Bugfixes:

Fixed an issue where technically invalid input would result in a
compiler error.

Features:

The markup class now inherits from the unicode string type such that
it's compatible with the string interface.

2.5.1 (2011-09-29)

Bugfixes:

The symbol names "convert", "decode" and "translate" are now no
longer set as read-only compiler internals. This fixes issue #65.
Fixed an issue where a macro extension chain nested two levels (a
template uses a macro that extends a macro) would lose the middle
slot definitions if slots were defined nested.

The compiler now throws an error if a nested slot definition is used
outside a macro extension context.

2.5.0 (2011-09-23)

Features:

An expression type structure: is now available which wraps the
expression result as structure such that it is not escaped on
insertion, e.g.::

${structure: context.body}

This also means that the structure keyword for tal:content
and tal:replace now has an alternative spelling via the
expression type structure:.
The string-based template constructor now accepts encoded input.

2.4.6 (2011-09-23)

Bugfixes:

The tal:on-error statement should catch all exceptions.
Fixed issue that would prevent escaping of interpolation expression
values appearing in text.

2.4.5 (2011-09-21)

Bugfixes:

The tal:on-error handler should have a error variable
defined that has the value of the exception thrown.
The tal:on-error statement is a substitution statement and
should support the "text" and "structure" insertion methods.

2.4.4 (2011-09-15)

Bugfixes:

An encoding specified in the XML document preamble is now read and
used to decode the template input to unicode. This fixes issue #55.
Encoded expression input on Python 3 is now correctly
decoded. Previously, the string representation output would be
included instead of an actually decoded string.
Expression result conversion steps are now correctly included in
error handling such that the exception output points to the
expression location.

2.4.3 (2011-09-13)

Features:

When an encoding is provided, pass the 'ignore' flag to avoid
decoding issues with bad input.

Bugfixes:

Fixed pypy compatibility issue (introduced in previous release).

2.4.2 (2011-09-13)

Bugfixes:

Fixed an issue in the compiler where an internal variable (such as a
translation default value) would be cached, resulting in variable
scope corruption (see issue #49).

2.4.1 (2011-09-08)

Bugfixes:

Fixed an issue where a default value for an attribute would
sometimes spill over into another attribute.
Fixed issue where the use of the default name in an attribute
interpolation expression would print the attribute value. This is
unexpected, because it's an expression, not a static text suitable
for output. An attribute value of default now correctly drops
the attribute.

2.4.0 (2011-08-22)

Features:

Added an option boolean_attributes to evaluate and render a
provided set of attributes using a boolean logic: if the attribute
is a true value, the value will be the attribute name, otherwise the
attribute is dropped.

In the reference implementation, the following attributes are
configured as boolean values when the template is rendered in
HTML-mode::
```
"compact", "nowrap", "ismap", "declare", "noshade",
"checked", "disabled", "readonly", "multiple", "selected",
"noresize", "defer"
```
Note that in Chameleon, these attributes must be manually provided.

Bugfixes:

The carriage return character (used on Windows platforms) would
incorrectly be included in Python comments.

It is now replaced with a line break.

This fixes issue #44.

2.3.8 (2011-08-19)

Fixed import error that affected Python 2.5 only.

2.3.7 (2011-08-19)

Features:

Added an option literal_false that disables the default behavior
of dropping an attribute for a value of False (in addition to
None). This modified behavior is the behavior exhibited in
reference implementation.

Bugfixes:

Undo attribute special HTML attribute behavior (see previous
release).

This turned out not to be a compatible behavior; rather, boolean
values should simply be coerced to a string.

Meanwhile, the reference implementation does support an HTML mode in
which the special attribute behavior is exhibited.

We do not currently support this mode.

2.3.6 (2011-08-18)

Features:

Certain HTML attribute names now have a special behavior for a
attribute value of True (or default if no default is
defined). For these attributes, this return value will result in the
name being printed as the value::

will be rendered as::

This behavior is compatible with the reference implementation.

2.3.5 (2011-08-18)

Features:

Added support for the set operator ({item, item, ...}).

Bugfixes:

If macro is defined on the same element as a translation name, this
no longer results in a "translation name not allowed outside
translation" error. This fixes issue #43.
Attribute fallback to dictionary lookup now works on multiple items
(e.g. d1.d2.d2). This fixes issue #42.

2.3.4 (2011-08-16)

Features:

When inserting content in either attributes or text, a value of
True (like False and None) will result in no
action.
Use statically assigned variables for "attrs" and
"default". This change yields a performance improvement of
15-20%.
The template loader class now accepts an optional argument
default_extension which accepts a filename extension which will
be appended to the filename if there's not already an extension.

Bugfixes:

The default symbol is now True for an attribute if the attribute
default is not provided. Note that the result is that the attribute
is dropped. This fixes issue #41.
Fixed an issue where assignment to a variable "type" would
fail. This fixes issue #40.
Fixed an issue where an (unsuccessful) assignment for a repeat loop
to a compiler internal name would not result in an error.
If the translation function returns the identical object, manually
coerce it to string. This fixes a compatibility issue with
translation functions which do not convert non-string objects to a
string value, but simply return them unchanged.

2.3.3 (2011-08-15)

Features:

The load: expression now passes the initial keyword arguments to
its template loader (e.g. auto_reload and encoding).
In the exception output, string variable values are now limited to a
limited output of characters, single line only.

Bugfixes:

Fixed horizontal alignment of exception location info
(i.e. 'String:', 'Filename:' and 'Location:') such that they match
the template exception formatter.

2.3.2 (2011-08-11)

Bugfixes:

Fixed issue where i18n:domain would not be inherited through macros
and slots. This fixes issue #37.

2.3.1 (2011-08-11)

Features:

The Builtin node type may now be used to represent any Python
local or global name. This allows expression compilers to refer to
e.g. get or getitem, or to explicit require a builtin object
such as one from the extra_builtins dictionary.

Bugfixes:

Builtins which are not explicitly disallowed may now be redefined
and used as variables (e.g. nothing).
Fixed compiler issue with circular node annotation loop.

2.3 (2011-08-10)

Features:

Added support for the following syntax to disable inline evaluation
in a comment:

Note that the initial question mark character (?) will be omitted
from output.
The parser now accepts '<' and '>' in attributes. Note that this is
invalid markup. Previously, the '<' would not be accepted as a valid
attribute value, but this would result in an 'unexpected end tag'
error elsewhere. This fixes issue #38.
The expression compiler now provides methods assign_text and
assign_value such that a template engine might configure this
value conversion to support e.g. encoded strings.

Note that currently, the only client for the assign_text method
is the string expression type.
Enable template loader for string-based template classes. Note that
the filename keyword argument may be provided on initialization
to identify the template source by filename. This fixes issue #36.
Added extra_builtins option to the page template class. These
builtins are added to the default builtins dictionary at cook time
and may be provided at initialization using the extra_builtins
keyword argument.

Bugfixes:

If a translation domain is set for a fill slot, use this setting
instead of the macro template domain.
The Python expression compiler now correctly decodes HTML entities
'gt' and 'lt'. This fixes issue #32.
The string expression compiler now correctly handles encoded text
(when support for encoded strings is enabled). This fixes issue #35.
Fixed an issue where setting the filename attribute on a
file-based template would not automatically cause an invalidation.
Exceptions raised by Chameleon can now be copied via
copy.copy. This fixes issue #36.
[leorochael]
If copying the exception fails in the exception handler, simply
re-raise the original exception and log a warning.

2.2 (2011-07-28)

Features:

Added new expression type load: that allows loading a
template. Both relative and absolute paths are supported. If the
path given is relative, then it will be resolved with respect to the
directory of the template.
Added support for dynamic evaluation of expressions.

Note that this is to support legacy applications. It is not
currently wired into the provided template classes.
Template classes now have a builtins attribute which may be used
to define built-in variables always available in the template
variable scope.

Incompatibilities:

The file-based template class no longer accepts a parameter
loader. This parameter would be used to load a template from a
relative path, using a find(filename) method. This was however,
undocumented, and probably not very useful since we have the
TemplateLoader mechanism already.
The compiled template module now contains an initialize function
which takes values that map to the template builtins. The return
value of this function is a dictionary that contains the render
functions.

Bugfixes:

The file-based template class no longer verifies the existence of a
template file (using os.lstat). This now happens implicitly if
eager parsing is enabled, or otherwise when first needed (e.g. at
render time).

This is classified as a bug fix because the previous behavior was
probably not what you'd expect, especially if an application
initializes a lot of templates without needing to render them
immediately.

2.1.1 (2011-07-28)

Features:

Improved exception display. The expression string is now shown in
the context of the original source (if available) with a marker
string indicating the location of the expression in the template
source.

Bugfixes:

The structure insertion mode now correctly decodes entities for
any expression type (including string:). This fixes issue #30.
Don't show internal variables in the exception formatter variable
listing.

2.1 (2011-07-25)

Features:

Expression interpolation (using the ${...} operator and
previously also $identifier) now requires braces everywhere
except inside the string: expression type.

This change is motivated by a number of legacy templates in which
the interpolation format without braces $identifier appears as
text.

2.0.2 (2011-07-25)

Bugfixes:

Don't use dynamic variable scope for lambda-scoped variables (#27).
Avoid duplication of exception class and message in traceback.
Fixed issue where a metal:fill-slot would be ignored if a macro
was set to be used on the same element (#16).

2.0.1 (2011-07-23)

Bugfixes:

Fixed issue where global variable definition from macro slots would
fail (they would instead be local). This also affects error
reporting from inside slots because this would be recorded
internally as a global.
Fixed issue with template cache digest (used for filenames); modules
are now invalidated whenever any changes are made to the
distribution set available (packages on sys.path).
Fixed exception handler to better let exceptions propagate through
the renderer.
The disk-based module compiler now mangles template source filenames
such that the output Python module is valid and at root level (dots
and hyphens are replaced by an underscore). This fixes issue #17.
Fixed translations (i18n) on Python 2.5.

2.0 (2011-07-14)

Point release.

2.0-rc14 (2011-07-13)

Bugfixes:

The tab character (\t) is now parsed correctly when used inside
tags.

Features:

The RepeatDict class now works as a proxy behind a separate
dictionary instance.
Added template constructor option keep_body which is a flag
(also available as a class attribute) that controls whether to save
the template body input in the body attribute.

This is disabled by default, unless debug-mode is enabled.
The page template loader class now accepts an optional formats
argument which can be used to select an alternative template class.

2.0-rc13 (2011-07-07)

Bugfixes:

The backslash character (followed by optional whitespace and a line
break) was not correctly interpreted as a continuation for Python
expressions.

Features:

The Python expression implementation is now more flexible for
external subclassing via a new parse method.

2.0-rc12 (2011-07-04)

Bugfixes:

Initial keyword arguments passed to a template now no longer "leak"
into the template variable space after a macro call.
An unexpected end tag is now an unrecoverable error.

Features:

Improve exception output.

2.0-rc11 (2011-05-26)

Bugfixes:

Fixed issue where variable names that begin with an underscore were
seemingly allowed, but their use resulted in a compiler error.

Features:

Template variable names are now allowed to be prefixed with a single
underscore, but not two or more (reserved for internal use).

Examples of valid names::

item
ITEM
_item
camelCase
underscore_delimited
help
Added support for Genshi's comment "drop" syntax::

Note the additional exclamation (!) character.

This fixes addresses issue #10.

2.0-rc10 (2011-05-24)

Bugfixes:

The tal:attributes statement now correctly operates
case-insensitive. The attribute name given in the statement will
replace an existing attribute with the same name, without respect to
case.

Features:

Added meta:interpolation statement to control expression
interpolation setting.

Strings that disable the setting: "off" and "false".
Strings that enable the setting: "on" and "true".
Expression interpolation now works inside XML comments.

2.0-rc9 (2011-05-05)

Features:

Better debugging support for string decode and conversion. If a
naive join fails, each element in the output will now be attempted
coerced to unicode to try and trigger the failure near to the bad
string.

2.0-rc8 (2011-04-11)

Bugfixes:

If a macro defines two slots with the same name, a caller will now
fill both with a single usage.
If a valid of None is provided as the translation function
argument, we now fall back to the class default.

2.0-rc7 (2011-03-29)

Bugfixes:

Fixed issue with Python 2.5 compatibility AST. This affected at
least PyPy 1.4.

Features:

The auto_reload setting now defaults to the class value; the
base template class gives a default value of
chameleon.config.AUTO_RELOAD. This change allows a subclass to
provide a custom default value (such as an application-specific
debug mode setting).

2.0-rc6 (2011-03-19)

Features:

Added support for target_language keyword argument to render
method. If provided, the argument will be curried onto the
translation function.

Bugfixes:

The HTML entities 'lt', 'gt' and 'quot' appearing inside content
subtition expressions are now translated into their native character
values. This fixes an issue where you could not dynamically create
elements using the structure (which is possible in ZPT). The
need to create such structure stems from the lack of an expression
interpolation operator in ZPT.
Fixed duplicate file pointer issue with test suite (affected Windows
platforms only). This fixes issue #9.
[oliora]
Use already open file using os.fdopen when trying to write out
the module source. This fixes LP #731803.

2.0-rc5 (2011-03-07)

Bugfixes:

Fixed a number of issues concerning the escaping of attribute
values:
1. Static attribute values are now included as they appear in the
  source.
  
  This means that invalid attribute values such as "true && false" are now left alone. It's not the job of the template
  engine to correct such markup, at least not in the default mode
  of operation.
2. The string expression compiler no longer unescapes
  values. Instead, this is left to each expression
  compiler. Currently only the Python expression compiler unescapes
  its input.
3. The dynamic escape code sequence now correctly only replaces
  ampersands that are part of an HTML escape format.

Imports:

The page template classes and the loader class can now be imported
directly from the chameleon module.

Features:

If a custom template loader is not provided, relative paths are now
resolved using os.abspath (i.e. to the current working
directory).
Absolute paths are normalized using os.path.normpath and
os.path.expanduser. This ensures that all paths are kept in
their "canonical" form.

2.0-rc4 (2011-03-03)

Bugfixes:

Fixed an issue where the output of an end-to-end string expression
would raise an exception if the expression evaluated to None (it
should simply output nothing).
The convert function (which is configurable on the template
class level) now defaults to the translate function (at
run-time).

This fixes an issue where message objects were not translated (and
thus converted to a string) using the a provided translate
function.
Fixed string interpolation issue where an expression immediately
succeeded by a right curly bracket would not parse.

This fixes issue #5.
Fixed error where tal:condition would be evaluated after
tal:repeat.

Features:

Python expression is now a TALES expression. That means that the
pipe operator can be used to chain two or more expressions in a
try-except sequence.

This behavior was ported from the 1.x series. Note that while it's
still possible to use the pipe character ("|") in an expression, it
must now be escaped.
The template cache can now be shared by multiple processes.

2.0-rc3 (2011-03-02)

Bugfixes:

Fixed atexit handler.

This fixes issue #3.
If a cache directory is specified, it will now be used even when not
in debug mode.
Allow "comment" attribute in the TAL namespace.

This fixes an issue in the sense that the reference engine allows
any attribute within the TAL namespace. However, only "comment" is
in common use.
The template constructor now accepts a flag debug which puts the
template instance into debug-mode regardless of the global
setting.

This fixes issue #1.

Features:

Added exception handler for exceptions raised while evaluating an
expression.

This handler raises (or attempts to) a new exception of the type
RenderError, with an additional base class of the original
exception class. The string value of the exception is a formatted
error message which includes the expression that caused the
exception.

If we are unable to create the exception class, the original
exception is re-raised.

2.0-rc2 (2011-02-28)

Fixed upload issue.

2.0-rc1 (2011-02-28)

Initial public release. See documentation for what's new in this
series.

Package profile

Chameleon

Releases

Release table

PyPI Downloads

Dependencies

Details

Project URLs

Dependencies

Package description