Query on Nested Functions

[Moses]

Hi

I have a nested function which works properly but I need to have a
slight change in it where I could not do that

Any help plz.

The Original function

function addSquares(b)
{
function square(a)
{
d = a*b;
return d;
}
return square;
}
t = addSquares(2)(2);

But What I need is before returning the square I need to do a small
validation to check weather d 10 , based upon that I need to return d
or return square.

ie

I need to change the function like this
function addSquares(b)
{
function square(a)
{
d = a*b;
return d;
}
t = square
if(t>10)
{
return 'Greater';
}
else
{

return t;
}
}
t = addSquares(2)(2);
But it gives error.

regards
moses

[Laurent Bugnion [MVP]]

Hi,

Moses wrote:

Hi

I have a nested function which works properly but I need to have a
slight change in it where I could not do that

Any help plz.

The Original function

function addSquares(b)
{
function square(a)
{
d = a*b;
return d;
}
return square;
}
t = addSquares(2)(2);

In that case, the "square" variable is actually a reference to a
Function object. In JavaScript, functions are also objects. This is what
allows you to return a reference to a function from another function,
and then to use the () notation to execute that returned function. It's
the same than saying (for example):

var a = function() { alert( 'Hello' ); };
a();

Though a is a variable, it accepts to be executed, because the
referenced function object understands the parenthesis.

But What I need is before returning the square I need to do a small
validation to check weather d 10 , based upon that I need to return d
or return square.

ie

I need to change the function like this
function addSquares(b)
{
function square(a)
{
d = a*b;
return d;
}
t = square
if(t>10)
{
return 'Greater';
}
else
{

return t;
}
}
t = addSquares(2)(2);

The problem here is that, based on the test, you return either a
reference to a function object (which can be executed), or a string
('Greater') which cannot be executed. This is why the error occurs.

You must redesign your functions with that in mind. Avoid changing the
type of the return value of a function (even though it is possible in
JavaScript), and you'll avoid such errors.

HTH,
Laurent
--
Laurent Bugnion [MVP ASP.NET]
Software engineering: http://www.galasoft-LB.ch
PhotoAlbum: http://www.galasoft-LB.ch/pictures
Support children in Calcutta: http://www.calcutta-espoir.ch

[RobG]

Moses wrote:

Hi

I have a nested function which works properly but I need to have a
slight change in it where I could not do that

Please don't post code with tabs, use 2 or 4 spaces for indenting.

The Original function

function addSquares(b)

The function name is confusing: why 'addSquares'? There is no addition
involved.

{
function square(a)
{
d = a*b;

You should keep d local with var:

var d = a*b;

But it isn't needed, consider:

function square(a) {
return a*b;
}

return d;
}
return square;
}
t = addSquares(2)(2);

The function seems unnecessarily convoluted.

But What I need is before returning the square I need to do a small
validation to check weather d 10 , based upon that I need to return d
or return square.

You can't make calling square conditional on the value of d since you
have to call square to find out what the value of d is.

Once square is called, d is a number. If you return d you will be
trying to evaluate d(2), which will result in an syntax error.

I need to change the function like this
function addSquares(b)
{
function square(a)
{
d = a*b;
return d;
}
t = square

That makes t a reference to the function square.

if(t>10)

Since t is a function object, trying to evaluate whether it is greater
than 10 doesn't make sense.

{
return 'Greater';
}
else
{

return t;
}
}
t = addSquares(2)(2);

I don't think I understand what you are trying to do. It seems you
want a function that takes two arguments. If the first is 10 or less,
return the product. If it's larger, return the first value.

A simple function to do that is:

function foo(a, b){
if (a 10) return a;
return a*b;
}
--
Rob

[Moses]

Hi

Thanks for all ur replys. I got some idea and I am redesigining my
function.

moses


RobG wrote:

Moses wrote:

Hi

I have a nested function which works properly but I need to have a
slight change in it where I could not do that

Please don't post code with tabs, use 2 or 4 spaces for indenting.

The Original function

function addSquares(b)

The function name is confusing: why 'addSquares'? There is no addition
involved.

{
function square(a)
{
d = a*b;

You should keep d local with var:

var d = a*b;

But it isn't needed, consider:

function square(a) {
return a*b;
}

return d;
}
return square;
}
t = addSquares(2)(2);

The function seems unnecessarily convoluted.

But What I need is before returning the square I need to do a small
validation to check weather d 10 , based upon that I need to return d
or return square.

You can't make calling square conditional on the value of d since you
have to call square to find out what the value of d is.

Once square is called, d is a number. If you return d you will be
trying to evaluate d(2), which will result in an syntax error.

I need to change the function like this
function addSquares(b)
{
function square(a)
{
d = a*b;
return d;
}
t = square

That makes t a reference to the function square.

if(t>10)

Since t is a function object, trying to evaluate whether it is greater
than 10 doesn't make sense.

{
return 'Greater';
}
else
{

return t;
}
}
t = addSquares(2)(2);

I don't think I understand what you are trying to do. It seems you
want a function that takes two arguments. If the first is 10 or less,
return the product. If it's larger, return the first value.

A simple function to do that is:

function foo(a, b){
if (a 10) return a;
return a*b;
}
--
Rob