Golang : When to use make or new?




Problem :

When to use make or new in Golang ? It can be confusing for newbie to Golang.

Solution :

In the simplest example that I can think of....

  • Imagine new as someone that creates an empty box and points the direction(pointer or address) of the empty box to you.
  • and make as someone that creates a box filled with values that defined by you and pass the non-empty box to you....not pointer or address.

Use new when you want to :

  • create a new file and save data to the the NEW file
  • create or allocate a new buffer for you to store some data, manipulate the buffer and then flush the data to somewhere else such as a pipe.

Use make when you want to :

  • use maps, slices and channels and want to manipulate the data in them directly instead of a pointer or address.
  • pre-fill the maps, slices and channels with initial values.
  • specify the size or increase/decrease the size of maps or slices during runtime.

Remember...the rule of the thumb is

  • new = empty box with pointer
  • make = filled box without pointer

Hope this simple tutorial can be useful to you. Happy coding!

Reference :

http://golang.org/doc/effectivego.html#allocationnew





By Adam Ng

IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.


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