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diff --git a/pkg_resources/api_tests.txt b/pkg_resources/api_tests.txt new file mode 100644 index 0000000..0a75170 --- /dev/null +++ b/pkg_resources/api_tests.txt @@ -0,0 +1,401 @@ +Pluggable Distributions of Python Software +========================================== + +Distributions +------------- + +A "Distribution" is a collection of files that represent a "Release" of a +"Project" as of a particular point in time, denoted by a +"Version":: + + >>> import sys, pkg_resources + >>> from pkg_resources import Distribution + >>> Distribution(project_name="Foo", version="1.2") + Foo 1.2 + +Distributions have a location, which can be a filename, URL, or really anything +else you care to use:: + + >>> dist = Distribution( + ... location="http://example.com/something", + ... project_name="Bar", version="0.9" + ... ) + + >>> dist + Bar 0.9 (http://example.com/something) + + +Distributions have various introspectable attributes:: + + >>> dist.location + 'http://example.com/something' + + >>> dist.project_name + 'Bar' + + >>> dist.version + '0.9' + + >>> dist.py_version == sys.version[:3] + True + + >>> print(dist.platform) + None + +Including various computed attributes:: + + >>> from pkg_resources import parse_version + >>> dist.parsed_version == parse_version(dist.version) + True + + >>> dist.key # case-insensitive form of the project name + 'bar' + +Distributions are compared (and hashed) by version first:: + + >>> Distribution(version='1.0') == Distribution(version='1.0') + True + >>> Distribution(version='1.0') == Distribution(version='1.1') + False + >>> Distribution(version='1.0') < Distribution(version='1.1') + True + +but also by project name (case-insensitive), platform, Python version, +location, etc.:: + + >>> Distribution(project_name="Foo",version="1.0") == \ + ... Distribution(project_name="Foo",version="1.0") + True + + >>> Distribution(project_name="Foo",version="1.0") == \ + ... Distribution(project_name="foo",version="1.0") + True + + >>> Distribution(project_name="Foo",version="1.0") == \ + ... Distribution(project_name="Foo",version="1.1") + False + + >>> Distribution(project_name="Foo",py_version="2.3",version="1.0") == \ + ... Distribution(project_name="Foo",py_version="2.4",version="1.0") + False + + >>> Distribution(location="spam",version="1.0") == \ + ... Distribution(location="spam",version="1.0") + True + + >>> Distribution(location="spam",version="1.0") == \ + ... Distribution(location="baz",version="1.0") + False + + + +Hash and compare distribution by prio/plat + +Get version from metadata +provider capabilities +egg_name() +as_requirement() +from_location, from_filename (w/path normalization) + +Releases may have zero or more "Requirements", which indicate +what releases of another project the release requires in order to +function. A Requirement names the other project, expresses some criteria +as to what releases of that project are acceptable, and lists any "Extras" +that the requiring release may need from that project. (An Extra is an +optional feature of a Release, that can only be used if its additional +Requirements are satisfied.) + + + +The Working Set +--------------- + +A collection of active distributions is called a Working Set. Note that a +Working Set can contain any importable distribution, not just pluggable ones. +For example, the Python standard library is an importable distribution that +will usually be part of the Working Set, even though it is not pluggable. +Similarly, when you are doing development work on a project, the files you are +editing are also a Distribution. (And, with a little attention to the +directory names used, and including some additional metadata, such a +"development distribution" can be made pluggable as well.) + + >>> from pkg_resources import WorkingSet + +A working set's entries are the sys.path entries that correspond to the active +distributions. By default, the working set's entries are the items on +``sys.path``:: + + >>> ws = WorkingSet() + >>> ws.entries == sys.path + True + +But you can also create an empty working set explicitly, and add distributions +to it:: + + >>> ws = WorkingSet([]) + >>> ws.add(dist) + >>> ws.entries + ['http://example.com/something'] + >>> dist in ws + True + >>> Distribution('foo',version="") in ws + False + +And you can iterate over its distributions:: + + >>> list(ws) + [Bar 0.9 (http://example.com/something)] + +Adding the same distribution more than once is a no-op:: + + >>> ws.add(dist) + >>> list(ws) + [Bar 0.9 (http://example.com/something)] + +For that matter, adding multiple distributions for the same project also does +nothing, because a working set can only hold one active distribution per +project -- the first one added to it:: + + >>> ws.add( + ... Distribution( + ... 'http://example.com/something', project_name="Bar", + ... version="7.2" + ... ) + ... ) + >>> list(ws) + [Bar 0.9 (http://example.com/something)] + +You can append a path entry to a working set using ``add_entry()``:: + + >>> ws.entries + ['http://example.com/something'] + >>> ws.add_entry(pkg_resources.__file__) + >>> ws.entries + ['http://example.com/something', '...pkg_resources...'] + +Multiple additions result in multiple entries, even if the entry is already in +the working set (because ``sys.path`` can contain the same entry more than +once):: + + >>> ws.add_entry(pkg_resources.__file__) + >>> ws.entries + ['...example.com...', '...pkg_resources...', '...pkg_resources...'] + +And you can specify the path entry a distribution was found under, using the +optional second parameter to ``add()``:: + + >>> ws = WorkingSet([]) + >>> ws.add(dist,"foo") + >>> ws.entries + ['foo'] + +But even if a distribution is found under multiple path entries, it still only +shows up once when iterating the working set: + + >>> ws.add_entry(ws.entries[0]) + >>> list(ws) + [Bar 0.9 (http://example.com/something)] + +You can ask a WorkingSet to ``find()`` a distribution matching a requirement:: + + >>> from pkg_resources import Requirement + >>> print(ws.find(Requirement.parse("Foo==1.0"))) # no match, return None + None + + >>> ws.find(Requirement.parse("Bar==0.9")) # match, return distribution + Bar 0.9 (http://example.com/something) + +Note that asking for a conflicting version of a distribution already in a +working set triggers a ``pkg_resources.VersionConflict`` error: + + >>> try: + ... ws.find(Requirement.parse("Bar==1.0")) + ... except pkg_resources.VersionConflict as exc: + ... print(str(exc)) + ... else: + ... raise AssertionError("VersionConflict was not raised") + (Bar 0.9 (http://example.com/something), Requirement.parse('Bar==1.0')) + +You can subscribe a callback function to receive notifications whenever a new +distribution is added to a working set. The callback is immediately invoked +once for each existing distribution in the working set, and then is called +again for new distributions added thereafter:: + + >>> def added(dist): print("Added %s" % dist) + >>> ws.subscribe(added) + Added Bar 0.9 + >>> foo12 = Distribution(project_name="Foo", version="1.2", location="f12") + >>> ws.add(foo12) + Added Foo 1.2 + +Note, however, that only the first distribution added for a given project name +will trigger a callback, even during the initial ``subscribe()`` callback:: + + >>> foo14 = Distribution(project_name="Foo", version="1.4", location="f14") + >>> ws.add(foo14) # no callback, because Foo 1.2 is already active + + >>> ws = WorkingSet([]) + >>> ws.add(foo12) + >>> ws.add(foo14) + >>> ws.subscribe(added) + Added Foo 1.2 + +And adding a callback more than once has no effect, either:: + + >>> ws.subscribe(added) # no callbacks + + # and no double-callbacks on subsequent additions, either + >>> just_a_test = Distribution(project_name="JustATest", version="0.99") + >>> ws.add(just_a_test) + Added JustATest 0.99 + + +Finding Plugins +--------------- + +``WorkingSet`` objects can be used to figure out what plugins in an +``Environment`` can be loaded without any resolution errors:: + + >>> from pkg_resources import Environment + + >>> plugins = Environment([]) # normally, a list of plugin directories + >>> plugins.add(foo12) + >>> plugins.add(foo14) + >>> plugins.add(just_a_test) + +In the simplest case, we just get the newest version of each distribution in +the plugin environment:: + + >>> ws = WorkingSet([]) + >>> ws.find_plugins(plugins) + ([JustATest 0.99, Foo 1.4 (f14)], {}) + +But if there's a problem with a version conflict or missing requirements, the +method falls back to older versions, and the error info dict will contain an +exception instance for each unloadable plugin:: + + >>> ws.add(foo12) # this will conflict with Foo 1.4 + >>> ws.find_plugins(plugins) + ([JustATest 0.99, Foo 1.2 (f12)], {Foo 1.4 (f14): VersionConflict(...)}) + +But if you disallow fallbacks, the failed plugin will be skipped instead of +trying older versions:: + + >>> ws.find_plugins(plugins, fallback=False) + ([JustATest 0.99], {Foo 1.4 (f14): VersionConflict(...)}) + + + +Platform Compatibility Rules +---------------------------- + +On the Mac, there are potential compatibility issues for modules compiled +on newer versions of Mac OS X than what the user is running. Additionally, +Mac OS X will soon have two platforms to contend with: Intel and PowerPC. + +Basic equality works as on other platforms:: + + >>> from pkg_resources import compatible_platforms as cp + >>> reqd = 'macosx-10.4-ppc' + >>> cp(reqd, reqd) + True + >>> cp("win32", reqd) + False + +Distributions made on other machine types are not compatible:: + + >>> cp("macosx-10.4-i386", reqd) + False + +Distributions made on earlier versions of the OS are compatible, as +long as they are from the same top-level version. The patchlevel version +number does not matter:: + + >>> cp("macosx-10.4-ppc", reqd) + True + >>> cp("macosx-10.3-ppc", reqd) + True + >>> cp("macosx-10.5-ppc", reqd) + False + >>> cp("macosx-9.5-ppc", reqd) + False + +Backwards compatibility for packages made via earlier versions of +setuptools is provided as well:: + + >>> cp("darwin-8.2.0-Power_Macintosh", reqd) + True + >>> cp("darwin-7.2.0-Power_Macintosh", reqd) + True + >>> cp("darwin-8.2.0-Power_Macintosh", "macosx-10.3-ppc") + False + + +Environment Markers +------------------- + + >>> from pkg_resources import invalid_marker as im, evaluate_marker as em + >>> import os + + >>> print(im("sys_platform")) + Invalid marker: 'sys_platform', parse error at '' + + >>> print(im("sys_platform==")) + Invalid marker: 'sys_platform==', parse error at '' + + >>> print(im("sys_platform=='win32'")) + False + + >>> print(im("sys=='x'")) + Invalid marker: "sys=='x'", parse error at "sys=='x'" + + >>> print(im("(extra)")) + Invalid marker: '(extra)', parse error at ')' + + >>> print(im("(extra")) + Invalid marker: '(extra', parse error at '' + + >>> print(im("os.open('foo')=='y'")) + Invalid marker: "os.open('foo')=='y'", parse error at 'os.open(' + + >>> print(im("'x'=='y' and os.open('foo')=='y'")) # no short-circuit! + Invalid marker: "'x'=='y' and os.open('foo')=='y'", parse error at 'and os.o' + + >>> print(im("'x'=='x' or os.open('foo')=='y'")) # no short-circuit! + Invalid marker: "'x'=='x' or os.open('foo')=='y'", parse error at 'or os.op' + + >>> print(im("'x' < 'y' < 'z'")) + Invalid marker: "'x' < 'y' < 'z'", parse error at "< 'z'" + + >>> print(im("r'x'=='x'")) + Invalid marker: "r'x'=='x'", parse error at "r'x'=='x" + + >>> print(im("'''x'''=='x'")) + Invalid marker: "'''x'''=='x'", parse error at "'x'''=='" + + >>> print(im('"""x"""=="x"')) + Invalid marker: '"""x"""=="x"', parse error at '"x"""=="' + + >>> print(im(r"x\n=='x'")) + Invalid marker: "x\\n=='x'", parse error at "x\\n=='x'" + + >>> print(im("os.open=='y'")) + Invalid marker: "os.open=='y'", parse error at 'os.open=' + + >>> em("sys_platform=='win32'") == (sys.platform=='win32') + True + + >>> em("python_version >= '2.7'") + True + + >>> em("python_version > '2.6'") + True + + >>> im("implementation_name=='cpython'") + False + + >>> im("platform_python_implementation=='CPython'") + False + + >>> im("implementation_version=='3.5.1'") + False |