assignment in if

[Gary Wessle]

Hi

is there a way to make an assignment in the condition of "if" and use
it later, e.g.

nx = re.compile('regex')
if nx.search(text):
funCall(text, nx.search(text))

nx.search(text) is evaluated twice, I was hoping for something like

nx = re.compile('regex')
if x = nx.search(text):
funCall(text, x))

thanks

 

[Ben Caradoc-Davies]

is there a way to make an assignment in the condition of "if"
No.

nx = re.compile('regex')
if x = nx.search(text):
funCall(text, x))

Use:

nx = re.compile('regex')
x = nx.search(text)
if x:
funCall(text, x)

 

[Roy Smith]

Hi

is there a way to make an assignment in the condition of "if" and use
it later, e.g.

nx = re.compile('regex')
if nx.search(text):
funCall(text, nx.search(text))

nx.search(text) is evaluated twice, I was hoping for something like

nx = re.compile('regex')
if x = nx.search(text):
funCall(text, x))

Personally, I find the C-style idiom you long for to be convenient and
useful. That being said, it does not exist in Python, by deliberate design
decision. In Python, assignment is not an operator with side effects like
in C or Java, but a statement. What you need to do is:

nx = re.compile('regex')
x = nx.search(text)
if x:
funCall(text, x))

The lack of embedded assignments leads to slightly more verbose code in
situations like this, but on the other hand, it avoids the typical C
disaster of writing a whole function as a one liner.

 

[Edward Elliott]

decision. In Python, assignment is not an operator with side effects like
in C or Java, but a statement.

<nitpick> assignemnt is actually an expression in those languages, not a

The lack of embedded assignments leads to slightly more verbose code in
situations like this, but on the other hand, it avoids the typical C
disaster of writing a whole function as a one liner.

Writing disasters in python just takes a little more creativity.

 

[Edward Elliott]

<nitpick> assignemnt is actually an expression in those languages, not a
statement. </nitpick>

s/statement/operator/

 

[Edward Elliott]

s/statement/operator/

<shakes head>
it was probably clearer the first time, but let me rephrase:
in C/Java, assignment is neither a statement not an operator. it is an
expression involving a certain operator. that operator (not so)
coincidentally happens to be the assignment operator, or one of its
variants.

ah forget it, replying to your reply to yourself is probably illegal...

 

[Bruno Desthuilliers]

Gary Wessle a écrit :

Hi

is there a way to make an assignment in the condition of "if" and use
it later
No.

, e.g.

nx = re.compile('regex')
if nx.search(text):
funCall(text, nx.search(text))

nx.search(text) is evaluated twice, I was hoping for something like

nx = re.compile('regex')
if x = nx.search(text):
funCall(text, x))

x = nx.search(text)
if x:
funCall(text, x)

 

[Bruno Desthuilliers]

Edward Elliott a écrit :

Roy Smith wrote:
(snip)


Writing disasters in python just takes a little more creativity.

+1 QOTW