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Begin

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

Begin["ctx"]`

sets the current context ($Context) to "ctx`", saving

Begin["Private"]

inside "MyPkg`" yields "MyPkg`Private`".

Notes the previous value for End\[\] to restore. If the argument starts with a backtick it is interpreted relative to the current context:

Examples (5)

Every input below was run against the current Mathilda build and its output recorded.

Applications (5)

In[1]:= $Context
Out[1]= "Global`"

In[2]:= Begin["foo`"]
Out[2]= "foo`"

In[3]:= $Context
Out[3]= "foo`"

In[4]:= End[]
Out[4]= "foo`"

In[5]:= $Context
Out[5]= "Global`"

Implementation notes

builtin_begin (src/context.c) takes a single string "ctx"and callscontext_begin, which pushes aFRAME_BEGINonto the internalg_stack(snapshotting the current context and search path), then setsg_currentto the new context. A leading-backtick argument like"Private"is interpreted relative to the current context (MyPkg` + `Private). republish_state refreshes the $Context/$ContextPath OwnValues, and the new current context string is returned. Invalid (non-backtick-terminated) specs emit Begin::cxt. The matching End[] (builtin_end) pops the frame to restore the saved context.

Attributes: Protected.

References

Notes & additional examples

Notes

Begin["ctx"]switches$Contexttoctxand saves the previous context so the matching `End[]` can restore it. An argument that starts with a backtick is taken relative to the current context (e.g. `Begin["`Private`"]` inside `MyPkg yields MyPkgPrivate``).