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How to check whether a file or directory exists?

...iven file or directory exists func exists(path string) (bool, error) { _, err := os.Stat(path) if err == nil { return true, nil } if os.IsNotExist(err) { return false, nil } return false, err } Edited to add error handling. ...
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How to search a Git repository by commit message?

... To search the commit log (across all branches) for the given text: git log --all --grep='Build 0051' To search the actual content of commits through a repo's history, use: git grep 'Build 0051' $(git rev-list --all) to show all instances of the given t...
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What is the LD_PRELOAD trick?

...ibrary (including the C runtime, libc.so). So to run ls with your special malloc() implementation, do this: $ LD_PRELOAD=/path/to/my/malloc.so /bin/ls share | improve this answer | ...
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What is a “callback” in C and how are they implemented?

...y're implemented using function pointers. Here's an example: void populate_array(int *array, size_t arraySize, int (*getNextValue)(void)) { for (size_t i=0; i<arraySize; i++) array[i] = getNextValue(); } int getNextRandomValue(void) { return rand(); } int main(void) { int m...
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What's Alternative to Singleton

...singleton in the unit testing because we can test different configurations all at once. 13 Answers ...
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Can't find the 'libpq-fe.h header when trying to install pg gem

...on Rails 3.1 pre version. I like to use PostgreSQL, but the problem is installing the pg gem. It gives me the following error: ...
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@Nullable annotation usage

...r pass a null" because I am dealing with uncontrollable third parties like API callers, database records, former programmers etc... so I am paranoid and defensive in approaches. Since you are on Java8 or later there is a bit cleaner approach than an if block. public String foo(@Nullable String mayB...
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How to prevent ifelse() from turning Date objects into numeric objects

...irst this felt a little "hackish" to me. But now I just think of it as a small price to pay for the performance returns that I get from ifelse(). Plus it's still a lot more concise than a loop. share | ...
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Is it possible to decompile a compiled .pyc file into a .py file?

... .pyc bytecode into .py, whereas unpyclib crashed with an exception. With all these tools, you get your code back including variable names, but without the comments. share | improve this answer ...
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Modular multiplicative inverse function in Python

... If you happen to be using sympy, then x, _, g = sympy.numbers.igcdex(a, m) does the trick. – Lynn Sep 16 '16 at 18:15 add a comment ...