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building strings from variables

P: n/a
Following a discussion with an associate at work about various ways to
build strings from variables in python, I'd like to hear your opinions
and preferred methods. The methods we discussed are:
1. some_string = "cd %s ; %s %d %s %s" % ( working_dir, ssh_cmd,
some_count, some_param1, some_param2)

2. import string
template = string.Template("cd $dir ; $cmd $count $param1
$param2")
some_string = template.substitute(dict(dir=working_dir,

cmd=ssh_cmd,

count=some_count,

pararm1=some_param1,

param2=some_param2))
here you can use a couple of nice tricks by using class.__dict__ and
globals() \ locals() dictionaries.

3. some_string = "cd "+working_dir+" ; "+ssh_cmd+ "
"+str(some_count)+" "+some_param1+" "+some_param2
(all these are supposed to produce the same strings)

Which methods do you know of \ prefer \ think is better because...?
I will appreciate any opinions about the matter.

Oct 5 '06 #1
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3 Replies


P: n/a

Gal Diskin wrote:
Following a discussion with an associate at work about various ways to
build strings from variables in python, I'd like to hear your opinions
and preferred methods. The methods we discussed are:
1. some_string = "cd %s ; %s %d %s %s" % ( working_dir, ssh_cmd,
some_count, some_param1, some_param2)

2. import string
template = string.Template("cd $dir ; $cmd $count $param1
$param2")
some_string = template.substitute(dict(dir=working_dir,

cmd=ssh_cmd,

count=some_count,

pararm1=some_param1,

param2=some_param2))
here you can use a couple of nice tricks by using class.__dict__ and
globals() \ locals() dictionaries.

3. some_string = "cd "+working_dir+" ; "+ssh_cmd+ "
"+str(some_count)+" "+some_param1+" "+some_param2
(all these are supposed to produce the same strings)

Which methods do you know of \ prefer \ think is better because...?
I will appreciate any opinions about the matter.
My opinion is that 1st method is the best. It's both very readable and
easy to write. 2nd way is too involved, and 3rd way is both hard to
read and difficult to compose. Another useful variant of method #1 is
to do this: %(varname)s ..." % globals()

Oct 5 '06 #2

P: n/a
Gal Diskin wrote:
Following a discussion with an associate at work about various ways to
build strings from variables in python, I'd like to hear your opinions
and preferred methods. The methods we discussed are:
1. some_string = "cd %s ; %s %d %s %s" % ( working_dir, ssh_cmd,
some_count, some_param1, some_param2)
....
Or another for readability:

4. some_string = ' '.join(["cd", working_dir, ";",
ssh_cmd, str(some_count), some_param1, some_param2])

--Scott David Daniels
sc***********@acm.org
Oct 5 '06 #3

P: n/a
Matthew Warren wrote:
-----Original Message-----
From:
py*******************************************@pyth on.org
[mailto:py***************************************** **@python.o
rg] On Behalf Of Gal Diskin
Sent: 05 October 2006 16:01
To: py*********@python.org
Subject: building strings from variables

Following a discussion with an associate at work about various ways to
build strings from variables in python, I'd like to hear your opinions
and preferred methods. The methods we discussed are:
1. some_string = "cd %s ; %s %d %s %s" % ( working_dir, ssh_cmd,
some_count, some_param1, some_param2)

2. import string
template = string.Template("cd $dir ; $cmd $count $param1
$param2")
some_string = template.substitute(dict(dir=working_dir,

cmd=ssh_cmd,

count=some_count,

pararm1=some_param1,

param2=some_param2))
here you can use a couple of nice tricks by using class.__dict__ and
globals() \ locals() dictionaries.

3. some_string = "cd "+working_dir+" ; "+ssh_cmd+ "
"+str(some_count)+" "+some_param1+" "+some_param2
(all these are supposed to produce the same strings)

Which methods do you know of \ prefer \ think is better because...?
I will appreciate any opinions about the matter.

:D

I think, it would depend really on what your aims are (readable code,
fast string generation...), and how the vars you want to build the
string from are respresented in your code (is it natural to use a dict
etc..)

I kicked off a conversation similar to this earlier today, and that was
my conclusion after helpful debate & advice.

Matt.
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Matt,
Thanks for replying. I tried looking up your discussion and I'm unsure
if I found the right post. Would you mind linking to it?

--
Gal Diskin
G_********@Intel.com
G_********@gmail.com
Work: +972-4-865-1637
Cell: +972-54-7594166

Oct 7 '06 #4

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