Best Practice for Library Building and Toolboxes

[SMcNeill]

And this type of thing can catch you when you least expect it.  Take a look at the glitchy code below:

Code: (Select All)

'This is my Program code area

Screen _NewImage(1280, 720, 32)

$Color:32

Option Base 1





Cls , Red

Sleep

FadeDown Blue

Sleep

FadeDown Yellow

Sleep

FadeDown White

Sleep

FadeDown Black







''$INCLUDE:'my file holding the library stuff below:

Sub FadeDown (colour As _Unsigned Long)



    Dim tempScreen(_Width - 1, _Height - 1) As _Unsigned Long

    Dim fade As _Unsigned Long

    For y = 0 To _Height - 1

        fade = _RGBA32(255 * (y / _Height) * _Red32(colour), 255 * (y / _Height) * _Green32(colour), 255 * (y / _Height) * _Blue32(colour), 255 * (y / _Height))

        For x = 0 To _Width - 1

            tempScreen(x, y) = Point(x, y) And fade

        Next

    Next

    For y = 0 To _Height - 1

        fade = _RGBA32(_Red32(colour), _Green32(colour), _Blue32(colour), _Height / y * 255)

        For x = 0 To _Width - 1

            PSet (x, y), tempScreen(x, y)

        Next

    Next

End Sub

Now, it's obvious that we're making an array that works on storing and changing our screen pixels.  Screens are  _Width -1,  _Height -1 in size, so we make the array to be to that size...   Nothing wrong with that.  Right?

Except we didn't explicitly define the bounds of our array and *assumed* that it'd be BASE 0.  With Option Base 1 in effect, we generate errors and crash.

Explicitly define your arrays in library codes.  Don't assume the base you're used to working in is what the public you share your code with, is going to be using.