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Abort makefile if variable not set
... an auxiliary function for that:
# Check that given variables are set and all have non-empty values,
# die with an error otherwise.
#
# Params:
# 1. Variable name(s) to test.
# 2. (optional) Error message to print.
check_defined = \
$(strip $(foreach 1,$1, \
$(call __check_defined,$...
Multiple aggregations of the same column using pandas GroupBy.agg()
... functions f1, f2 to the same column df["returns"] , without having to call agg() multiple times?
3 Answers
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How can I make a UITextField move up when the keyboard is present - on starting to edit?
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isn't it batter to call -(void)setViewMovedUp:(BOOL)movedUp in keyBoardWillSHow and KeyBoardWillHide events!!
– Abduliam Rehmanius
Jun 26 '11 at 4:08
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Does setting Java objects to null do anything anymore?
... object chain A->B->C, then once A is not reachable, A, B and C will all be eligible for garbage collection (assuming nothing else is referring to either B or C). There's no need, and never has been any need, to explicitly set references A->B or B->C to null, for example.
Apart from tha...
How can I build a small operating system on an old desktop computer? [closed]
...in, as I know writing an operating system is unbearably complicated (especially by oneself).
20 Answers
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Why Func instead of Predicate?
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Well, actually you have to place that in the context of the guideline, which is about writing a LINQ provider. So yeah, for LINQ operators, the guideline is to use Func<> and Expression<> as parameters for the extension met...
Python (and Python C API): __new__ versus __init__
...vs immutable types.
__new__ accepts a type as the first argument, and (usually) returns a new instance of that type. Thus it is suitable for use with both mutable and immutable types.
__init__ accepts an instance as the first argument and modifies the attributes of that instance. This is inappropr...
When to use the different log levels
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I generally subscribe to the following convention:
Trace - Only when I would be "tracing" the code and trying to find one part of a function specifically.
Debug - Information that is diagnostically helpful to people more than just...
Re-raise exception with a different type and message, preserving existing information
...ns that it can raise (e.g. inheriting from a FooError abstract class for all the foo module's specific exceptions). This allows users of the module to catch those particular exceptions and handle them distinctly, if needed. But many of the exceptions raised from the module are raised because of ...
How to send a “multipart/form-data” with requests in python?
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Basically, if you specify a files parameter (a dictionary), then requests will send a multipart/form-data POST instead of a application/x-www-form-urlencoded POST. You are not limited to using actual files in that dictionary, howe...