CODEWITHSUNDEEP
pythonsyntax
user5474086
user5474086

Reputation:

Define an operator that's not already built into the syntax

I'd like to know if there is a way to define a operation that isn't built into Python - rather than creating some member function of an object and calling it.

For example, define an "absolute value" operation for a class C, then invoke it as |C|.

If not, I know it's possible to import operations (I think abs val is in math), so could I look up the tags for operations I import? By "tag" I mean what would replace eq in def __eq__(self):

or is there no "tag" for imported operations?

Upvotes: 0

Views: 51

Answers (2)

ivan_pozdeev
ivan_pozdeev

Reputation: 35998

Python's syntax is defined by the interpreter's implementation. You cannot add your own syntax without modifying it.

Unless you somehow manage to "preprocess" the source into the "normal" form before it reaches the interpreter.

You may have some luck with PyPy where the interpreter is implemented in Python itself. You need to make a separate unit of "normal" code that would

  • somehow access PyPy's objects (e.g. by importing corresponding modules)
  • modify them
  • feed the "unusual" source to the modified interpreter

Do note that your proposed construct will need to be parsed and thus be distinguishable from other language constructs. Your |x| is, at first sight, indistinguishable from the | operator (bitwize OR).

Upvotes: 2

glglgl
glglgl

Reputation: 91017

If I understand, you want to add something to the already existing "mappings" , such as

+ --> __add__
& --> __and__

etc.?

Then I have to disappoint you - you cannot define such a thing as 

|...| --> __abs__.

Upvotes: 1

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