Migrating from older APIs

This section has information on migrating from older APIs.

The pkg_resources resource API

Basic resource access

resource_exists(package, resource_name)

finder(package).find(resource_name) is not None

resource_stream(package, resource_name)

finder(package).find(resource_name).as_stream()

resource_string(package, resource_name)

finder(package).find(resource_name).bytes

resource_isdir(package, resource_name)

finder(package).find(resource_name).is_container

resource_listdir(package, resource_name)

finder(package).find(resource_name).resources

Resource extraction

resource_filename(package, resource_name)

finder(package).find(resource_name).file_path

set_extraction_path(extraction_path)

This has no direct analogue, but you can achieve equivalent results by doing something like the following:

from distlib import resources

resources.cache = resources.Cache(extraction_path)

before accessing the file_path property of any Resource. Note that if you have accessed the file_path property for a resource before doing this, the cache may already have extracted files.

cleanup_resources(force=False)

This is not actually implemented in pkg_resources – it’s a no-op. You could achieve the analogous result using:

from distlib import resources

not_removed = resources.cache.clear()

Provider interface

You can provide an XXXResourceFinder class which finds resources in custom storage containers, and works like ResourceFinder. Although it shouldn’t be necessary, you could also return a subclass of Resource from your finders, to deal with custom requirements which aren’t catered for.

get_cache_path(archive_name, names=())

There’s no analogue for this, as you shouldn’t need to care about whether particular resources are implemented in archives or not. If you need this API, please give feedback with more information about your use cases.

extraction_error()

There’s no analogue for this. The Cache.get() method, which writes a resource’s bytes to a file in the cache, will raise any exception caused by underlying I/O. If you need to handle this in the cache layer, you can subclass Cache and override get(). If that doesn’t work for you, please give feedback with more information about your use cases.

postprocess(tempname, filename)

There’s no analogue for this. The Cache.get() method, which writes a resource’s bytes to a file in the cache, can be overridden to perform any custom post-processing. If that doesn’t work for you, please give feedback with more information about your use cases.

The pkg_resources entry point API

Entry points in pkg_resources are equivalent to per-distribution exports dictionary (see Exporting things from Distributions). The keys to the dictionary are just names in a hierarchical namespace delineated with periods (like Python packages). These keys are called groups in pkg_resources documentation, though that term is a little ambiguous. In Eclipse, for example, they are called extension point IDs, which is a little closer to the intended usage, but a bit of a mouthful. In distlib, we’ll use the term category or export category.

In distlib, the implementation of exports is slightly different from entry points of pkg_resources. A Distribution instance has an exports attribute, which is a dictionary keyed by category and whose values are dictionaries that map names to ExportEntry instances.

Below are the pkg_resources functions and how to achieve the equivalent in distlib. In cases where the pkg_resources functions take distribution names, in distlib you get the corresponding Distribution instance, using:

dist = dist_path.get_distribution(distname)

and then ask that instance (or the dist_path instance) for the things you need.

load_entry_point(distname, groupname, name)

dist.exports[groupname][name].value

get_entry_info(distname, groupname, name)

dist.exports[groupname][name]

get_entry_map(distname, groupname=None)

dist.exports or dist.exports[groupname]

iter_entry_points(groupname, name=None)

dist_path.get_exported_entries(groupname, name=None)

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