How to Find Out Where a Function Is Defined

How to find out where a function is defined?

You could also do this in PHP itself:

$reflFunc = new ReflectionFunction('function_name');
print $reflFunc->getFileName() . ':' . $reflFunc->getStartLine();

How to find the file where a function is defined?

The environment()-function will return the package in which a function is "located" after it is loaded.

> environment(facet_grid)
<environment: namespace:ggplot2>

After downloading ggplot2_version_whatever.tag.gz from CRAN (or perhaps github) and expanding it, you can find (using your system text search facilities) a file named facet-grid.r that has this definiton starting at line 125:

facet_grid <- function(facets, margins = FALSE, scales = "fixed", space = "fixed", shrink = TRUE, labeller = "label_value", as.table = TRUE, switch = NULL, drop = TRUE) {

You should find more comments. Comments are dropped during compiling unless you make special efforts to retain them.

Finding out where a function is defined

It is defined in this file.

See line 64:

int name##_RemoveIndex(name##_p name, int index); 

For the definition of name## you need to dig the linked file and the documentation.

determine from which file a function is defined in python

func.__module__

Will return the module in witch it is defined

func.__globals__['__file__']

will return the whole path of the file where it is defined.Only for user defined functions

Finding out where a function was defined in zsh

Well, zsh stores the functions internally, but I guess you want to know where zsh read the function from. This can be shown by:

whence -v FUNCTIONNAME

Find out where a function comes from?

Get yourself a good IDE such as netbeans or eclipse. They have functionality to find function declarations, and also find the usages of those functions (under refactoring).

Personally I use netbeans. I simply have to ctrl-click on a function name & netbeans will find where the function is defined, and automatically open the file for me.

Find where a python function is defined

So I've been in this exact scenario, and my process was as follows:

Scenario where file2.py includes statements like from file1 import *.

1. In file1.py, I would copy all the import statements, and paste them in file2.py
2. I would copy all the top-level function/class names, and set them up as comma-delimited, and replace the * in file2.py: from file1 import file1_method1, file1_method2, file1_class1.
   
   I don't have VS Code, but I'm sure there's a way to look at the File Structure view and copy the list and reformat it into the import statement.
3. Repeat steps 1-2 for every from x import *, it's best to start from core files, and then work your way out to dependent files (reduce work for nested import * statements)
4. Search file2.py for any eval() statements which may reference other modules, and manually import those. If no eval(), then skip.
5. Optional: Sort the import statements (yay OCD!)
6. Once this is done, I let the linter work, and remove all unused references (including duplicate imports) except those needed by eval, perhaps add comment for linter to ignore these.
7. Run your code, and pray you didn't make mistakes (nothing to worry if you didn't!)
8. Repeat 1-7 for every file in your application!
9. ???
10. Profit!

This has been tough, but really has been worth it after all that work to trace what is being used and where in each file.

Find function definition in C++

The easiest solution would be to use grep (with find to get results very fast) like this:

find srcDir -name "*.c" -o -name "*.cpp" -print0 | xargs -0 grep "functionName"

The Makefile based solution is to change the linking so you ask for a verbose location of a function definition like this (if you use GCC) (you can also do that on the command line with "make LDFLAGS=...seebelow...")

# In your makefile, locate this:
LDFLAGS:= ...
# Replace by this
LDFLAGS:= -Wl,--trace-symbol=functionName

This results in:

$ gcc -o test main.o -Wl,--trace-symbol=main
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crt1.o: reference to main
main.o: definition of main

This solution is useful if you have plenty of similar function name, and you actually want the one that's used in the final binary.

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