Package: grokcore.chameleon
grokcore.chameleongrokcore.chameleonmakes it possible to use Chameleon page templates in Grok.
For more information on Grok and Chameleon page templates see:http://pagetemplates.org/http://pagetemplates.org/docs/latest/http://pypi.python.org/pypi/Chameleonhttp://grok.zope.org/Contentsgrokcore.chameleonInstallationUsageDetailed DescriptionChameleon Zope page templatesPrerequisitesSimple templatesSubstituting variablesSupported variablesInline TemplatesTAL expressionsTranslationMacrosDifferences from regular Zope page templatesCHANGES4.0 (2023-02-09)3.0.1 (2018-01-12)3.0.0 (2018-01-11)1.0.4 (2014-07-29)1.0.3 (2012-10-12)1.0.2 (2012-05-07)1.0.1 (2012-05-03)1.0 (2012-05-01)1.0rc4 (2012-01-03)1.0rc3 (2011-07-14)Earlier versionsInstallationNote that future versions of grok will depend itself on grokcore.chameleon
and configure it. In other words, chameleon-based templates will be available
by default from that version on!To use Chameleon page templates with Grok all you need is to install
grokcore.chameleon as an egg and include its ZCML. The best place to do
this is to makegrokcore.chameleona dependency of your application by
adding it to yourinstall_requireslist insetup.cfg. If you
used grokproject to create your applicationsetup.pyis located in the
project root. It should look something like this:install_requires=['setuptools',
                  'grokcore.chameleon',
                  # Add extra requirements here
                  ],Note that if you use theallow-picked-versions= falsedirective in your
project’sbuildout.cfg, you will have to add version number specifications
for several packages to your[versions]section.Then includegrokcore.chameleonin yourconfigure.zcml. If you used
grokproject to create your application it’s atsrc/<projectname>/configure.zcml. Add the include line after the include
line for grok, but before the grokking of the current package. It should look
something like this:<include package="grok" />
<include package="grokcore.chameleon" />
<grok:grok package="." />If you useautoIncludein yourconfigure.zcml, you should not
have to do this latter step.Then runbin/buildoutagain. You should now see buildout saying
something like (where version numbers can vary):Getting distribution for 'grokcore.chameleon'.
Got grokcore.chameleon 0.5.That’s all. You can now start using Chameleon page templates in your
Grok application.Usagegrokcore.chameleonsupports the Grok standard of placing templates in a
templates directory, for exampleapp_templates, so you can use Chameleon
page templates by simply placing the Chameleon page templates in the templates
directory, just as you would with regular ZPT templates.Although chameleon templates themselves do not have a standard for the file
extensions for templates, Grok needs to have an association between an filename
extension and a template language implementation so it knows which
implementation to use.grokcore.chameleondeclares to use the extension*.cpt(Chameleon page template) for Chameleon page templates.You can also use Chameleon page templates inline. The syntax for this
is:from grokcore.chameleon.components import ChameleonPageTemplate
index = ChameleonPageTemplate('<html>the html code</html>')Or if you use files:from grokcore.chameleon.components import ChameleonPageTemplateFile
index = ChameleonPageTemplateFile(filename='thefilename.html')Detailed DescriptionGrok-support for using chameleon driven templates.Withgrokcore.chameleonyou can use templates parsed and rendered byChameleonusing the Zope Page Template templating language.Chameleon Zope page templatesChameleon provides support for Zope page templates which can be used
from grok writing templates with the.cpt(=Chameleon Page
Template) filename extension.Chameleon page templates differ from standard Zope page templates in a
few aspects, most notably:Expressions are parsed inPython-modeby default. This means,
instead oftal:content="view/value"you must usetal:content="view.value". Every occurence of TAL-expressions
starting withpython:now can be shortened by skipping this
marker.Also Genshi-like variable substitutions are supported. For example
you can write${myvar}instead oftal:content="myvar".Beside this, most rules for regular Zope page templates apply also to
chameleon page templates.See theChameleonpage for more information.PrerequisitesBefore we can see the templates in action, we care for correct
registration and set some used variables:>>> import os
>>> testdir = os.path.join(os.path.dirname(__file__), 'tests')
>>> cpt_fixture = os.path.join(testdir, 'cpt_fixture')
>>> template_dir = os.path.join(cpt_fixture, 'app_templates')We register everything. Before we can grok our fixture, we have to
grok thegrokcore.chameleonpackage. This way the new template types
are registered with the framework:>>> import grokcore.view
>>> grokcore.view.testing.grok('grokcore.chameleon')
>>> grokcore.view.testing.grok('grokcore.chameleon.tests.cpt_fixture')We create a mammoth, which should provide us a bunch of chameleon page
template driven views and put it in the database to setup location
info:>>> from grokcore.chameleon.tests.cpt_fixture.app import Mammoth
>>> manfred = Mammoth()
>>> getRootFolder()['manfred'] = manfredFurthermore we prepare for getting the different views on manfred:>>> from zope.publisher.browser import TestRequest
>>> from zope.component import getMultiAdapter
>>> request = TestRequest()Simple templatesWe prepared a plain cavepainting view. The template looks like this:>>> cavepainting_cpt = os.path.join(template_dir, 'cavepainting.cpt')
>>> with open(cavepainting_cpt, 'r') as f:
...     print(f.read())
<html>
  <body>
    A cave painting.
  </body>
</html>The rendered view looks like this:>>> view = getMultiAdapter((manfred, request),
...                         name='cavepainting')
>>> print(view())
<html>
  <body>
    A cave painting.
  </body>
</html>Substituting variablesA template can access variables likeview,context,staticand its methods and attributes. Thefoodview does exactly
this. The template looks like this:>>> food_cpt = os.path.join(template_dir, 'food.cpt')
>>> with open(food_cpt, 'r') as f:
...     print(f.read())
<html>
<body>
<span tal:define="foo 'a FOO'">
${view.me_do()}
<span tal:replace="structure view.me_do()" />
CSS-URL: ${path:static/test.css}
My context is: ${view.url(context)}
${foo}
<span tal:replace="foo" />
</span>
</body>
</html>The rendered view looks like this:>>> view = getMultiAdapter((manfred, request), name='food')
>>> print(view())
<html>
<body>
<span>
&lt;ME GROK EAT MAMMOTH!&gt;
<ME GROK EAT MAMMOTH!>
CSS-URL: dummy:/test.css
My context is: http://127.0.0.1/manfred
a FOO
a FOO
</span>
</body>
</html>As we can see, there is a difference between Genshi-like substitution
and TAL-like substitution: while both expressions:${view.me_do()}and:<span tal:replace="view.me_do()" />actually render the same string<ME GROK EAT MAMMOTH!>, the former
does this straight and plain, while the latter performs additionally
HTML-encoding of the string. Therefore the output of both expressions
differ. It’s:<ME GROK EAT MAMMOTH!>for the former expression and:&lt;ME GROK EAT MAMMOTH!&gt;for the latter.Supported variablesEach template provides at least the following vars:templatethe template instanceviewthe associated viewcontextthe context of the viewrequestthe current requestas we can see, when we look at thevars.cptfrom our fixture:>>> cpt_file = os.path.join(template_dir, 'vars.cpt')
>>> with open(cpt_file, 'r') as f:
...     print(f.read())
<html>
<body>
This template knows about the following vars:
<BLANKLINE>
  template (the template instance):
   ${template}
<BLANKLINE>
  view (the associated view):
   ${view}
<BLANKLINE>
  context (the context of the view):
   ${context}
<BLANKLINE>
  request (the current request):
   ${request}
</body>
</html>and render it:>>> view = getMultiAdapter((manfred, request), name='vars')
>>> print(view())
<html>
<body>
This template knows about the following vars:
<BLANKLINE>
  template (the template instance):
   &lt;PageTemplateFile ...vars.cpt&gt;
<BLANKLINE>
  view (the associated view):
   &lt;grokcore.chameleon.tests.cpt_fixture.app.Vars object at 0x...&gt;
<BLANKLINE>
  context (the context of the view):
   &lt;grokcore.chameleon.tests.cpt_fixture.app.Mammoth object at 0x...&gt;
<BLANKLINE>
  request (the current request):
   CONTENT_LENGTH:  0
GATEWAY_INTERFACE:  TestFooInterface/1.0
HTTP_HOST:  127.0.0.1
SERVER_URL: http://127.0.0.1
</body>
</html>Custom template namespace names are supported:>>> view = getMultiAdapter((manfred, request), name='namespace')
>>> print(view())
<html>
<body>
This template knows about the following custom namespace name:
<BLANKLINE>
  myname:
   Henk
<BLANKLINE>
</body>
</html>Inline TemplatesWe can also define inline templates. In ourapp.pywe defined an
inline template like this:from grokcore.chameleon import components

...

class Inline(grokcore.view.View):
  sometext = 'Some Text'

inline = components.ChameleonPageTemplate(
    "<html><body>ME GROK HAS INLINES! ${view.sometext}</body></html>")If we render this view we get:>>> view = getMultiAdapter((manfred, request), name='inline')
>>> print(view())
<html><body>ME GROK HAS INLINES! Some Text</body></html>TAL expressionsStarting withgrokcore.chameleon0.5 we deploy the all-in-oneChameleonpackage.What TAL/TALES expressions in templates are supported depends mainly
from the installed version ofChameleon, while we support some
additional, Zope-related TALES expressions.A list of all supported expressions and statements can be found at thechameleon.zpt documentation. The additional
TALES expressions provided bygrokcore.chameleonare:existsTell whether a name exists in the templates’ namespace.notEvaluate the expression to a boolean value and invert it.pathHandle the expression as a path and not as a Python expression.providerSupport for viewlet providers.NoteStarting withgrokcore.chameleon0.5 support for the
Python expressionexists()has been dropped. The TALES
expressionexists: path/to/somethingis still available.In ourapp.pywe defined a special view for showing some special
expressions. This also includes a viewlet:import grok
from grokcore.chameleon import components

class Mammoth(grok.Application, grok.Container):
    pass

...

class Expressions(grok.View):
    pass

class MainArea(grok.ViewletManager):
    grok.name('main')

class MainContent(grok.Viewlet):
    grok.view(Expressions)
    grok.viewletmanager(MainArea)
    def render(self):
        return 'Hello from viewlet'Now we can make use of the TALES expressionsnot:,path:,exists:andprovider:in theexpressions.cpttemplate of
our fixture:>>> cpt_file = os.path.join(template_dir, 'expressions.cpt')
>>> with open(cpt_file, 'r') as f:
...     print(f.read())
<html>
<body>
  <div tal:define="food 'Yummy Dinoburger'"
       tal:omit-tag="">
    <!-- We support `exists` -->
    <div tal:condition="exists: food">
      ${food}
    </div>
<BLANKLINE>
    <!-- We support `not` -->
    <div tal:content="not: food" />
    <div tal:content="not('food')" />
    <div tal:content="not: 1 in [2,3]" />
    <div tal:content="not: not: food" />
<BLANKLINE>
    <!-- We support `path` -->
    <div tal:content="path: food/upper" />
<BLANKLINE>
    <!-- We support `provider` -->
    <tal:main content="structure provider:main" />
<BLANKLINE>
  </div>
</body>
</html>and render it:>>> view = getMultiAdapter((manfred, request), name='expressions')
>>> print(view())
<html>
<body>
<BLANKLINE>
    <!-- We support `exists` -->
    <div>
      Yummy Dinoburger
    </div>
<BLANKLINE>
    <!-- We support `not` -->
    <div>False</div>
    <div>False</div>
    <div>True</div>
    <div>True</div>
<BLANKLINE>
    <!-- We support `path` -->
    <div>YUMMY DINOBURGER</div>
<BLANKLINE>
    <!-- We support `provider` -->
    Hello from viewlet
<BLANKLINE>
<BLANKLINE>
</body>
</html>Translation>>> # Monkeypatch zope.i18n.negotiate
>>> import zope.i18n
>>> import zope.i18n.config
>>> print(getMultiAdapter((manfred, request), name='menu')())
<html>
<body>
  <h1>Menu</h1>
  <ol>
    <li>Deepfried breaded veal cutlets</li>
  </ol>
</body>
</html>>>> # What's for food today in Germany?
>>> # We need to monkey patch the language settings for this test.
>>> old_1, old_2 = zope.i18n.negotiate, zope.i18n.config.ALLOWED_LANGUAGES
>>> zope.i18n.negotiate = lambda context: 'de'
>>> zope.i18n.config.ALLOWED_LANGUAGES = ['de']
>>> print(getMultiAdapter((manfred, request), name='menu')())
<html>
<body>
  <h1>Menu</h1>
  <ol>
    <li>Schnitzel</li>
  </ol>
</body>
</html>>>> # Restore the monkey patch.
>>> zope.i18n.negotiate, zope.i18n.config.ALLOWED_LANGUAGES = old_1, old_2MacrosWithgrokcore.chameleonwe can also use macros, although it is a bit
different from regular Zope page templates.We can define macros like this:>>> cpt_file = os.path.join(template_dir, 'macromaster.cpt')
>>> with open(cpt_file, 'r') as f:
...     print(f.read())
<p xmlns:metal="http://xml.zope.org/namespaces/metal"
   metal:define-macro="hello">
  Hello from <b metal:define-slot="name">macro master</b>
</p>The defined macrohellocan be rendered in another Chameleon
template with the METAL attributeuse-macro.To refer to a local macro, i.e. a macros defined in the same template,
you can use something like:<div metal:use-macro="template.macros['<macro-name>']">
  Replaced by macro
</div>where<macro-name>must be an existing macro name.To refer to macros in external templates, you must use thepath:expression
like this:<div metal:use-macro="path:
  context/@@<viewname>/template/macros/<macro-name>">
   Replaced by external macro
</div>where<viewname>refers to an existing view oncontextandmacro- nameagain refers to an existing macro in the specified template.Note, that this is different from how you refer to macros in standard Zope page
templates. The short notationview/macros/<macro-name>works only with
regular Zope page templates.The following template makes use of both methods:>>> cpt_file = os.path.join(template_dir, 'macrouser.cpt')
>>> with open(cpt_file, 'r') as f:
...     print(f.read())
<html xmlns:metal="http://xml.zope.org/namespaces/metal">
<body>
  <p metal:define-macro="hello">
    Hi there from macro user!
  </p>
  <div metal:use-macro="template.macros['hello']">
    Fill this
  </div>
<BLANKLINE>
  <div metal:use-macro="path: context/@@macromaster/template/macros/hello">
    <b metal:fill-slot="name">user slot</b>
    Fill this too
  </div>
</body>
</html>When rendered also the slot defined in the master template is filled by macro
user content:>>> cpt_file = os.path.join(template_dir, 'macrouser.cpt')
>>> view = getMultiAdapter((manfred, request), name='macrouser')
>>> print(view())
<html>
<body>
  <p>
    Hi there from macro user!
  </p>
  <p>
    Hi there from macro user!
  </p>
<BLANKLINE>
<BLANKLINE>
  <p>
  Hello from <b>user slot</b>
<BLANKLINE>
</p>
</body>
</html>Clean up:>>> del getRootFolder()['manfred']Differences from regular Zope page templatesMacros are referenced differently. See appropriate section above.Expressions are parsed inPython-modeby default. This means, instead
oftal:content="view/value"you must usetal:content="view.value".
Every occurence of TAL-expressions starting withpython:now can be
shortened by skipping this marker.CHANGES4.0 (2023-02-09)Drop support for Python 2.7, 3.4, 3.5, 3.6.Add support for Python 3.7, 3.8, 3.9, 3.10, 3.11.3.0.1 (2018-01-12)Rearrange tests such that Travis CI can pick up all functional tests too.3.0.0 (2018-01-11)Python 3 compatibility.1.0.4 (2014-07-29)Improve the performances of the translate mechanism with Chameleon
2.10 or more recent.1.0.3 (2012-10-12)Fix broken translations when using Chameleon 2.9 or more recent.1.0.2 (2012-05-07)With not using the z3c.pt PageTemplateFile baseclass, the behaviour of
finding the template file relative to the module was lost. This has been
fixed.1.0.1 (2012-05-03)Make sure the minimal version requirements are defined.1.0 (2012-05-01)Thetarget_languagemangling was lost in version 1.0rc4.
Copied from z3c.pt.1.0rc4 (2012-01-03)Update to newes Chameleon 2.7.1Using some Components/Expressions directly from Chameleon instead of z3c.pt1.0rc3 (2011-07-14)Rename megrok.chameleon into grokcore.chameleon to make it an official part
of Grok.Earlier versionsEarlier versions of grokcore.chameleon came by the name megrok.chameleon.