CODEWITHSUNDEEP
rfunction
Sam Weisenthal
Sam Weisenthal

Reputation: 2951

Using argument of outer function as global variable for a function defined inside outer function - "function factory"

Is this bad practice? It seems like a lot could go wrong here.*

I am setting the argument of an outer function to be a global variable for a function defined inside it. I am just doing this to work around some existing code.

f = function(a,b){h = function(c){print(b);b+c}}
myh  = f(1,2)
myh(7)

#[1] 2
#[1] 9

*On the other hand, it's perfectly acceptable to write something like

h = function(c){print(7);7+c}

Upvotes: 0

Views: 27

Answers (1)

Joel Kandiah
Joel Kandiah

Reputation: 1525

Creating a function that creates functions (or a function factory) is a totally acceptable code practice. See https://adv-r.hadley.nz/function-factories.html for more details on certain parts of the technical implementation in R.

It is most often used if you need to create functions at runtime or you need to create a lot of similar funcions.

The function factory you have created could be considered similar to a function factory that would create different sized counters that told the user how much the amount was incremented by.

It is important to keep track of the functions you create this way however.

Let me know if you'd like more clarification on anything.

(One possible bad practise in the function you have created though is an unused argument a).

Upvotes: 2

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