Version 15 of namespace import

namespace import imports commands into a namespace.

Synopsis

namespace import ?-force? ?pattern pattern ...?

Documentation

official reference

Description

Each pattern is qualified name, the tail of which is a glob-style pattern that selects the commands in the specified namespace. glob-style characters only have their glob pattern meanings in the tail component of pattern. In the namespace qualifiers of pattern they have no special meaning. The commands that match the pattern and that are exported from the specified namespace are imported into the current namespace, meaning that a new command is created in the current namespace as an alias to the exported command in the specified namespace. renaming such an alias does not break the alias.

namespace import normally returns an error if an imported command conflicts with an existing command. However, if the -force option is given, imported commands will silently replace existing commands.

namespace import has snapshot semantics: Only matching commands that are currently defined in the exporting namespace are imported. In other words, you can import only the commands that are in a namespace at the time when namespace import is executed. To import a command, namespace import must be called after that command has been exported. This is in contrast to namespace export whose patterns apply to all commands in the namespace, regardless of when they were defined.

For use cases where it is an alternative, namespace path is preferred to namespace import. (PYK 2014-06-22: rationale needed).

To find the origin of the commands returned by calling namespace import with no arguments, use namespace origin.

Examples:

namespace import ::foo::x
namespace import a::p*

Misc

escargo 2006-12-04: I tested this to see what namespace import returns, and it didn't return anything. There are two behaviors that I think might be useful that aren't implemented:

Have namespace import return a list of the commands that are imported. Right now I don't see any easy way to determine what gets imported. (DKF: This is what 8.5 now does, BTW.) (What TIP 261 specifies is the behavior with no arguments. That's not quite what I'm suggesting.)
Alternatively, have namespace import take another parameter, perhaps -asif, that tells the it to just return the names of what would be imported and to not do the actual import.

My motivation has to do with Nagelfar, actually. The second option would allow a code analyzer to follow along with "package require" and "namespace import" to discover code that would be known to the code being analyzed. This would allow reduction of false positives for unknown commands.