Begin

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`Begin`

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Begin["context`"]

resets the current context.

Details

Begin resets the value of $Context.
The interpretation of symbol names depends on context. Begin thus affects the parsing of input expressions.

Examples

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Basic Examples (1)Summary of the most common use cases

Define a function f in the MyContext` Context:

In[1]:=1

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https://wolfram.com/xid/0giv4y-j5jw7v

Out[1]=1

In[2]:=2

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https://wolfram.com/xid/0giv4y-j8alxw

Restore the context:

In[3]:=3

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https://wolfram.com/xid/0giv4y-s71x2

Out[3]=3

f will generally be hidden in the restored context:

In[4]:=4

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https://wolfram.com/xid/0giv4y-l3yd9x

The definitions are all in MyContext`f :

In[5]:=5

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https://wolfram.com/xid/0giv4y-clpsxx

The function can be called using its fully qualified name:

In[6]:=6

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https://wolfram.com/xid/0giv4y-et9jyh

Out[6]=6

Applications (1)Sample problems that can be solved with this function

Make symbols used for package function definitions private, reducing the possibility for conflict:

In[1]:=1

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https://wolfram.com/xid/0giv4y-haa4ep

Out[1]=1

Any use of the symbol f in the package context ensures that f is created in that context:

In[2]:=2

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https://wolfram.com/xid/0giv4y-dtxgtq

When the context given to Begin starts with ` it extends from the current context:

In[3]:=3

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https://wolfram.com/xid/0giv4y-mdu8qx

Out[3]=3

In[4]:=4

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https://wolfram.com/xid/0giv4y-bubg65

In[5]:=5

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https://wolfram.com/xid/0giv4y-por66k

Out[5]=5

In[6]:=6

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https://wolfram.com/xid/0giv4y-mgttio

Since the symbol f is in the package context, the function works after EndPackage:

In[7]:=7

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https://wolfram.com/xid/0giv4y-ga3wqo

Out[7]=7

You can see that the other variable uses the private context:

In[8]:=8

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https://wolfram.com/xid/0giv4y-ia4f0s

Properties & Relations (3)Properties of the function, and connections to other functions

Begin["cont`"] sets $Context to "cont`":

In[1]:=1

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https://wolfram.com/xid/0giv4y-7m7isf

Out[2]=2

Out[3]=3

End restores $Context to its value before the matching Begin:

In[4]:=4

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https://wolfram.com/xid/0giv4y-foci5r

Out[5]=5

Unlike BeginPackage, Begin does not modify $ContextPath:

In[1]:=1

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https://wolfram.com/xid/0giv4y-f64hii

Out[1]=1

Similarly, End does not modify it, either:

In[2]:=2

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https://wolfram.com/xid/0giv4y-54u8m

Out[2]=2

Begin does not alter the value of $ContextAliases:

In[1]:=1

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https://wolfram.com/xid/0giv4y-097mdd

Out[1]=1

End restores $ContextAliases to its value before the matching Begin:

In[2]:=2

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https://wolfram.com/xid/0giv4y-8614wm

Out[2]=2

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