# Module tf.about.usefunc

## Summary

The function use() lets you make use of a corpus in the same way as the use statements in MySQL and MongoDb let you make use of a database. It loads the features of a corpus plus extra modules, it loads the Text-Fabric app or a customization of it, and makes it all available in an API. If any of the above mentioned ingredients is not locally available on your computer, it will auto-download it, subject to checkout specifiers that you provide.

### Basic usage:

A = use("org/repo")


or

A = use("org/repo:specapp", checkout="specdata")

A = use("org/repo:specapp", checkout="specdata", backend="gitlab.huc.knaw.nl")


See tf.about.corpora for a list of known corpora that can be loaded this way.

### Full usage

A = use(
"org/repo:specapp",
backend=None,     # e.g. "gitlab.huc.knaw.nl"
checkout=None, # e.g. "latest"
version=None,  # e.g. "1.2.3"
mod=None,      # e.g. "org1/repo1/path1:specmod1,org2/repo2/path2:specmod2"
setFile=None,  # e.g. "path/to/file"
legacy=False,
hoist=globals(),
locations=None,
modules=None,
volume=None,
collection=None,
silent=False,
**configOverrides,
)


### Legacy usage:

A = use("corpus")


or

A = use("corpus", legacy=True)


## Security

Security warning

Text-Fabric apps may be downloaded from GitHub/GitLab and then imported as a module and then executed.

Do you trust the downloaded code? Make sure you know the repository where the code comes from, and the people who own the repository.

Security note

## Details

When loading a corpus via this method, most of the features in view will be loaded and made available. However, some Text-Fabric apps may exclude some features from being automatically loaded. And in general, features whose names start with omap@ will not be automatically loaded. Any of these features can be loaded on demand later by means of App.load().

During start-up the following happens:

1. the corpus data may be downloaded to your ~/text-fabric-data directory, if not already present there;
3. most features of the corpus are loaded into memory.
4. the data is inspected to derive configuration information for the advanced API; if present, additional settings, code and styling is loaded.

1. load the app of the corpus (config setting, static material, python code)
2. load the data of the corpus.

Both items can be specified independently, in terms of where they reside locally or online. Such a specification consists of a path and a checkout specifier. The path part looks like a directory, and specifies a location inside a repository, e.g. etcbc/bhsa. The checkout specifier part is a keyword:

• local under your local directory ~/text-fabric-data
• clone under your local directory ~/github
• latest under the latest release, to be checked with online backend
• hot under the latest commit, to be checked with online backend
• v1.2.3 under release v1.2.3, to be fetched from online backend
• 123aef under commit 123aef, to be fetched from online backend
• absent under your local directory ~/text-fabric-data if present, otherwise the latest release on backend, if present, otherwise the latest commit on backend

For a demo, see banks/repo.

## Specifying app and/or data

By default, the online repository for apps and data is GitHub (https://github.com).

But you can also use GitLab instances. You do that by specifying the server location in the parameter backend, e.g.

    backend="gitlab"

    backend="gitlab.knaw.huc.nl"


Synonyms:

• None, "", github.com, github
• gitlab.com, gitlab

The specification of the app is in the first argument: app-path:app-checkout-specifier The normal case is where app-path has the form org/repo pointing to a repository that holds the corpus, both app and data. If we find an app under app-path, it will have information about where the data is, so the data-path is known. The data-checkout-specifier is passed as an optiona argument: checkout=data-checkout-specifier.

So far we have described how to use a TF corpus which has an app inside in the standard location, i.e. as org/repo/app . But app and data may also reside in arbitrary places, and for that there is additional syntax in the first argument:

• app:full/path/to/tf/app Specify the location of the app. You may not append a checkout specifier to this.

• data:full/path/to/tf/data/version Do not try to find an app, but point to the data instead (a generic TF app with default settings will be used). You may pass a checkout specifier by appending :xxx.

• corpus legacy way of calling an app by its name only. Find a TF app in repo annotation/app-corpus.

Without legacy=True, you get a warning, and TF assumes the TF app has been migrated from annotation/app-corpus to org/repo/app, and it loads the app from there.

If you pass legacy=True you do not get that warning, and TF loads the app from annotation/app-corpus.

You have to use this if you go back in the history to times where the legacy method was the only method of loading a corpus. The older history of the app is preserved in annotation/app-corpus, but not in the migrated org/repo/app.

## Versions

Text-Fabric expects that the data resides in version directories. The configuration of a TF-app specifies which version will be used. You can override that by passing the optional argument version="x.y.z". Where we do not have a TF-app that specifies the version, i.e. if you pass a data:path/to/tf/data string you must either:

• specify the paths so that they include the version directory
• specify the path to the parent of the version directories and pass version="x.y.z"

Modules

If you also ask for extra data modules by means of the mod argument, then the corresponding version of those modules will be chosen. Every properly designed data module must refer to a specific version of the main source!

## Modules and sets

Besides the main corpus data, you can also draw in other data.

### Modules

They are typically sets of features provides by others to enrich or comment the main corpus. A module is specified in much the same way as the main corpus data. The optional mod argument is a comma-separated list or an iterable of modules in one of the forms

{org}/{repo}/{path}


or

{org}/{repo}/{path}:data-checkout-specifier


All features of all those modules will be loaded. If they are not yet present, they will be downloaded from a backend first. For example, there is an easter egg module on GitHub, and you can obtain it by

mod='etcbc/lingo/easter/tf'


Here the {org} is etcbc, the {repo} is lingo, and the {path} is easter/tf under which version c of the feature egg is available in TF format. You can point to any such directory om the entire GitHub if you know that it contains relevant features.

Your TF app might be configured to download specific modules. See moduleSpecs in the app's config.yaml file. If you need these specific module with a different checkout specifier, you can override those by passing those modules in this parameter explicitly.

Hint

This is needed for example if you specify a specific release for the core data module. The associated standard modules probably do not have that exact same release, so you have to look up their releases in GitHub/GitLab, and attach the release numbers found to the module specifiers.

Let TF manage your text-fabric-data directory

It is better not to fiddle with your ~/text-fabric-data directory manually. Let it be filled with auto-downloaded data. You can then delete data sources and modules when needed, and have them redownloaded at your wish, without any hassle or data loss.

### Sets

They are named nodesets, that, when imported, can be used in search templates as if they were node types. You can construct them in a Python program and then write them to disk with writeSets(). When you pass that file path with setFile=path/to/file, the named sets will be loaded by Text-Fabric.

See also Search.search() and readSets().

## Overrides

Sometimes you need to deviate from settings that have been specified in the TF app that you invoke. Or you want to set things explicitly when you do not invoke a TF app. You can prepare a dictionary of such settings, say configOverrides, and pass the contents as keyword arguments: **configOverrides. The list of possible settings is spelled out in tf.advanced.settings.

Corpus has moved

Suppose you want to work with an older version of the corpus. A complication occurs if the repo has been renamed and/or moved to an other organization. When you go back in the history and download an older version of the app, its configuration settings specify a different org, repo and relative path than what is currently the case. Here the possibility to override settings come to the rescue.

A good example is in clariah/wp6-missieven which resided in annotation/clariah-gm before, and in Dans-labs/clariah-gm even earlier.

When we want to migrate manual annotations made against the 0.4 version to the 0.7 version, we run into this issue. But we can still load the 0.4 version by means of

A = use( "missieven:v0.4", checkout="clone", version="0.4", hoist=globals(), legacy=True, provenanceSpec=dict(org="clariah", repo="wp6-missieven"), )

## Hoisting

The result of A = use() is that the variable A holds an object, the TF-app, loaded in memory, offering an API to the corpus data. You get that API by api = A.api, and then you have access to the particular members such as

• F = api.F (see NodeFeature)
• L = api.L (see Locality)
• T = api.T (see Text)
• TF = api.TF (see FabricCore)

If you work with one corpus in a notebook, this gets cumbersome. You can inject the global variables F, L, T, TF and a few others directly into your program by passing hoist=globals(). See the output for a list wof the new globals that you have got this way. Do not do this if you work with several corpora or several versions of a corpus in the same program!

## Volumes and collections

Instead of loading a whole corpus, you can also load individual volumes or collections of individual volumes of it. If your work is confined to a volume or collection, it might pay off to load only the relevant pieces of the corpus. Text-Fabric will maintain the details of the relationship between the parts and the whole.

Volumes and collections

It is an error to load a volume as a collection and vice-versa

You get a warning if you pass both a volume and a collection. The collection takes precedence, and the volume is ignored in that case.

### Volumes

If you pass volume=volume-heading TF will load a single volume of the work, specified by its heading. The volume is stored in a directory with .tf files, located under the directory _local which is in the same directory as the .tf files of the work. See tf.about.volumes.

### Collections

If you pass collection="collection-name" TF will load a single named collection of volumes of the work. The collection is stored in a directory with .tf files, located under the directory _local which is in the same directory as the .tf files of the work. See tf.about.volumes.

## Lower level

### locations, modules

You can add other directories that TF will search for feature files. They can be passed with the locations and modules optional parameters. For the precise meaning of these parameters see FabricCore.

More, not less

Using these arguments will load features on top of the default selection of features. You cannot use these arguments to prevent features from being loaded. Read on to see how you can achieve the loading of fewer features.

### api

So far, A = use() will construct an advanced API with a more or less standard set of features loaded, and make that API avaible to you, under A.api. But you can also setup a core API yourself by usin the lower level method FabricCore with your choice of locations and modules:

from tf.fabric import Fabric
TF = Fabric(locations=..., modules=...)


Here you have full control over what you load and what not. If you want the extra power of the TF app, you can wrap this api:

A = use("org/repo", api=api)


or

A = use("app:path/to/app", api=api)


etc.

Some apps do not load all available features of the corpus by default.

This happens when a corpus contains quite a number of features that most people never need. Loading them cost time and takes a lot of RAM.

In the case where you need an available feature that has not been loaded, you can load it by demanding

TF.load('feature1 feature2', add=True)

provided you have used the hoist=globals() parameter earlier. If not, you have to say

Loading a corpus can be quite noisy in the output. You can reduce that by means of the slient paramenter. If True, nearly all output of this call will be suppressed, including the links to the loaded data, features, and the API methods. Error messages will still come through. If deep, all output will be suppressed, except errors.
"""
"""