Professional IronPython

TAblE 12-3: 
Warning Message Categories
ClASS 
dESCRIPTIoN
DeprecationWarning 
Used to display warnings about applications that use deprecated 
(outdated) features. Normally, these warnings provide an alterna-
tive feature you should use in place of the deprecated feature.
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Understanding IronPython Warnings
 
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251
ClASS 
dESCRIPTIoN
FutureWarning 
Used to display warnings about applications that use features 
that will change sometime in the future. For example, the class, 
method, attribute, or function might change in an update of the 
Python specification. In most cases, you should keep the future 
update in mind, but not change your application today unless 
the new feature is available and debugged.
ImportWarning 
Triggered when an application imports a module. The module 
is still usable and likely doesn’t contain any problems (unless 
you see other warnings). The interpreter generally ignores 
these warnings.
PendingDeprecationWarning 
Used to display warnings about applications that use
features that will be deprecated sometime in the future (as 
opposed to the change indicated by the FutureWarning cat-
egory). In most cases, you won’t need to change your applica-
tion immediately, but you should change it to use an updated 
feature soon.
RuntimeWarning 
Specifies that one or more features are based on suspect run-
time functionality (such as modules that aren’t fully tested). In 
most cases, this warning indicates that your application is likely 
to fail more often or suffer other reliability issues.
SyntaxWarning 
Indicates that the application will run, but that it contains some 
suspect syntax. Perhaps the syntax isn’t approved or is simply 
non-standard. Finding standardized methods for creating the 
application syntax is a good way to avoid this warning.
UnicodeWarning 
Triggered whenever an application experiences some problem 
with Unicode implementation. Although this warning may not 
affect some languages, it could affect languages that rely on an 
extended character set.
UserWarning 
Provides the default category for the 
warn()
function. This 
warning level is for issues related to user code. For example, 
input from a user code function is supposed to provide the loca-
tion of a logging file on disk, but your module can’t find the log-
ging file. Your code won’t fail without the information, but it can’t 
create the logging information either. 
Warning 
Provides the implementation of all warning subclasses.
It’s a subclass of the 
Exception
class. This is a warning
category that you use to create new warning categories. 
There is never a good reason to use this category to generate 
warning messages.
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