Restrict parameter count for optional parameters in php

Question

From the php documentation i came across the following function:

string number_format ( float $number , int $decimals = 0 , 
                       string $dec_point = '.' , string $thousands_sep = ',' )

This function accepts either one, two, or four parameters (not three). When passed three arguments, the function generates a warning Warning: Wrong parameter count for number_format() on the line of function call.

From what I understand, any optional parameter should be totally optional. Also, php does not support function overloading so that we could have made two different functions to achieve this.

My questions are:

Is it possible to somehow restrict the number of arguments as above in the function declaration itself (not within the function code)
If not, and that the above function uses trigger_error() to generate the warning, how does the generated warning refer to the file and line from where this function is being called from. trigger_error() function seems to generate a warning / error on the line it is called.

php.net/manual/en/function.trigger-error.php ?

Benjamin Gruenbaum
– Benjamin Gruenbaum

2013-05-07 04:09:57 +00:00
Commented May 7, 2013 at 4:09 — Benjamin Gruenbaum
– Benjamin Gruenbaum, Commented May 7, 2013 at 4:09

Raptor · Accepted Answer · 2013-05-07 04:09:40Z

0

The function just adds an additional check of whether you have 3 parameters or not.

If 3 parameters are sent, it generates a warning.

Similar to :

if(func_num_args() == 3) {
  trigger_error('Wrong parameter count for number_format()', E_USER_WARNING);
}

Reference: func_num_args() , trigger_error()

answered May 7, 2013 at 4:09

Raptor

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4 Comments

Adwiv Over a year ago

But will it not generate the warning on a line within the library where this function is defined. In this case, the warning is shown on the line where the function is being called.

Raptor Over a year ago

similar logic is defined in PHP parser. that's why PHP parser will raise Warning in function definition level.

Adwiv Over a year ago

I have updated the question. I want to understand that logic and whether it is possible to implement it in some of our own functions. The trigger_error raises the warning on the file / line it is used.

Raptor Over a year ago

you can control the output buffer & show only the errors on the page , i.e. make use of ob_*() functions.

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