Difference between revisions of "Python templates"

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(New page: Category:Engineering Category:Python Python has an excellent built-in template system -- the % operator. Granted this is not what many people would consider a "real" template syst...)
 
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[[Category:Engineering]]
 
[[Category:Engineering]]
 
[[Category:Python]]
 
[[Category:Python]]
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== Python string templates using the % template operator ==
  
 
Python has an excellent built-in template system -- the % operator.
 
Python has an excellent built-in template system -- the % operator.
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it's much more powerful than most people give it credit for.
 
it's much more powerful than most people give it credit for.
  
Combine % with the locals() function and template code practically writes itself.
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The key is to combine % with the locals() function. Template code practically writes itself.
 
Remember string templates can have more than just %d and %s style replacements.
 
Remember string templates can have more than just %d and %s style replacements.
 
It can also take a dictionary, like %(DICT_KEY1)s or %(DICT_KEY2)d.
 
It can also take a dictionary, like %(DICT_KEY1)s or %(DICT_KEY2)d.
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<pre>
 
<pre>
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# This is a string template to format an email.
 
TEMPLATE="""From: %(FROM)s
 
TEMPLATE="""From: %(FROM)s
 
To: %(TO)s
 
To: %(TO)s
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"""
 
"""
  
def send_alert (USERNAME, FROM, TO, SUBJECT):
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def send_alert (USERNAME, FROM, TO, SUBJECT, LIMIT, USED):
     USERNAME = "xxx"
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     return TEMPLATE % locals()
    EMAIL = "user@example.com
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</pre>
    print TEMPLATE % locals()
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 +
Running the template will give the following results:
 +
<pre>
 +
>>> print send_alert ('Joe Bloe', 'root@example.com', 'jbloe@example.com', 'over quota', 1000, 1234)
 +
From: root@example.com
 +
To: jbloe@example.com
 +
Hello Joe Bloe,
 +
Subject: over quota
 +
 
 +
Your account is over quota.
 +
Your quota limit is 1000 bytes.
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Your amount used is 1234 bytes.
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>>>
 
</pre>
 
</pre>

Revision as of 16:26, 6 June 2007


Python string templates using the % template operator

Python has an excellent built-in template system -- the % operator. Granted this is not what many people would consider a "real" template system, but it's much more powerful than most people give it credit for.

The key is to combine % with the locals() function. Template code practically writes itself. Remember string templates can have more than just %d and %s style replacements. It can also take a dictionary, like %(DICT_KEY1)s or %(DICT_KEY2)d. Next remember that the locals() function returns a dictionary of local variables. This makes it trivial to merge local variables into a string template.

# This is a string template to format an email.
TEMPLATE="""From: %(FROM)s
To: %(TO)s
Hello %(USERNAME)s,
Subject: %(SUBJECT)s

Your account is over quota. 
Your quota limit is %(LIMIT)d bytes.
Your amount used is %(USED)d bytes.

"""

def send_alert (USERNAME, FROM, TO, SUBJECT, LIMIT, USED):
    return TEMPLATE % locals()

Running the template will give the following results:

>>> print send_alert ('Joe Bloe', 'root@example.com', 'jbloe@example.com', 'over quota', 1000, 1234)
From: root@example.com
To: jbloe@example.com
Hello Joe Bloe,
Subject: over quota

Your account is over quota. 
Your quota limit is 1000 bytes.
Your amount used is 1234 bytes.

>>>