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How to get the original value of an attribute in Rails
...flow.com/a/50973808/9359123
Appending _was is deprecated in rails 5.1, now you should append _before_last_save
Something like:
before_save object
do_something_with object.name_before_last_save
end
Will return the name value before your last save at database (works for save and create)
The...
Iterating through a JSON object
...nt:
from __future__ import print_function
for song in json_object:
# now song is a dictionary
for attribute, value in song.items():
print(attribute, value) # example usage
NB: You could use song.iteritems instead of song.items if in Python 2.
...
Re-raise exception with a different type and message, preserving existing information
...ture, the __cause__ attribute is set. The built-in exception handler also knows how to report the exception's “cause” and “context” along with the traceback.
In Python 2, it appears this use case has no good answer (as described by Ian Bicking and Ned Batchelder). Bummer.
...
Parse a .py file, read the AST, modify it, then write back the modified source code
...asy, without writing new .py files! If you expand your question to let us know what you actually want to accomplish, new .py files will probably not be involved in the answer at all; I have seen hundreds of Python projects doing hundreds of real-world things, and not a single one of them needed to e...
How to set versionName in APK filename using gradle?
... Is there any way to add variant.buildType.name to the name? I know this isn't really default config related, but I'm trying to figure out how to remove the obsolete variantOutput.getAssemble() warning
– Allan W
Mar 5 '19 at 5:51
...
How do I print the elements of a C++ vector in GDB?
...db wiki page particularly readable, maybe because it's "slightly" outdated now? For instance, I had the impression that the suggested content of the $HOME/.gdbinit was necessary. At the moment I end up with no such file at all and gdb correctly showing the content of std::vector. However, since duri...
How do I use IValidatableObject?
...
The problem with this solution is that now you depend on the caller for your object to be properly validated.
– cocogza
Feb 28 '17 at 22:06
...
Python strftime - date without leading 0?
...>>> '{dt.year}/{dt.month}/{dt.day}'.format(dt = datetime.datetime.now())
'2013/4/19'
Though perhaps beyond the scope of the original question, for more interesting formats, you can do stuff like:
>>> '{dt:%A} {dt:%B} {dt.day}, {dt.year}'.format(dt=datetime.datetime.now())
'Wedne...
How to disable python warnings
...s warnings section of the python docs?
If you are using code that you know will raise a warning, such as a deprecated function, but do not want to see the warning, then it is possible to suppress the warning using the catch_warnings context manager:
import warnings
def fxn():
warnings.war...
When should I use the Visitor Design Pattern? [closed]
...
(Suppose it is a complex hierarchy with a well-established interface.)
Now we want to add a new operation to the hierarchy, namely we want each animal to make its sound. As far as the hierarchy is this simple, you can do it with straight polymorphism:
class Animal
{ public: virtual void makeSou...