Question

This line doesn’t make much sense, but I wonder why it raises a syntax error:

x = 1; if x: with open("x.txt") as f: f.write(x)

How can I execute with block after if statement in one line?

Answer 1

The with statement is a red herring. Even the following is syntax error:

>>> x = 1; if x: if x: print x
  File "<stdin>", line 1
    x = 1; if x: if x: print x
            ^
SyntaxError: invalid syntax

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See here:

http://docs.python.org/reference/compound_stmts.html

A suite can be one or more semicolon-separated simple statements on the same line as the header, following the header’s colon, or it can be one or more indented statements on subsequent lines. Only the latter form of suite can contain nested compound statements; the following is illegal, mostly because it wouldn’t be clear to which if clause a following else clause would belong:

if test1: if test2: print x