With
Statement block to allow implicit access to fields in a user defined type variable
With user_defined_var
The With...End With block allows the omission of the name of a variable of a user-defined Type when referring to its fields. The fields may then be accessed with just a single period (.) before them, e.g. if the Type contains an field element called "element", then it could be accessed within the With block as ".element".
It can be used as a shorthand to save typing and avoid cluttering the source. With can also be used with dereferenced pointers, as the second example shows.
With blocks may be nested. In this case, only the innermost With block is active, and any outer ones are ignored until the inner one is closed again. See the third example for an illustration of this.
Internally, a reference to the variable is taken at the start of the With block, and then is used to calculate any element accesses within the block. Note that this means that Goto should not be used to jump into a With block, otherwise the reference will not have been set, and the results of trying to access it will be undefined.
Syntax
With user_defined_var
statements
End WithDescription
The With...End With block allows the omission of the name of a variable of a user-defined Type when referring to its fields. The fields may then be accessed with just a single period (.) before them, e.g. if the Type contains an field element called "element", then it could be accessed within the With block as ".element".
It can be used as a shorthand to save typing and avoid cluttering the source. With can also be used with dereferenced pointers, as the second example shows.
With blocks may be nested. In this case, only the innermost With block is active, and any outer ones are ignored until the inner one is closed again. See the third example for an illustration of this.
Internally, a reference to the variable is taken at the start of the With block, and then is used to calculate any element accesses within the block. Note that this means that Goto should not be used to jump into a With block, otherwise the reference will not have been set, and the results of trying to access it will be undefined.
Example
Type rect_type
x As Single
y As Single
End Type
Dim the_rectangle As rect_type
Dim As Integer temp, t
With the_rectangle
temp = .x
.x = 234 * t + 48 + .y
.y = 321 * t + 2
End With
x As Single
y As Single
End Type
Dim the_rectangle As rect_type
Dim As Integer temp, t
With the_rectangle
temp = .x
.x = 234 * t + 48 + .y
.y = 321 * t + 2
End With
Type rect_type
x As Single
y As Single
End Type
Dim the_rectangle As rect_type Ptr
the_rectangle = CAllocate( 5 * Len( rect_type ) )
Dim As Integer loopvar, temp, t
For loopvar = 0 To 4
With the_rectangle[loopvar]
temp = .x
.x = 234 * t + 48 + .y
.y = 321 * t + 2
End With
Next
x As Single
y As Single
End Type
Dim the_rectangle As rect_type Ptr
the_rectangle = CAllocate( 5 * Len( rect_type ) )
Dim As Integer loopvar, temp, t
For loopvar = 0 To 4
With the_rectangle[loopvar]
temp = .x
.x = 234 * t + 48 + .y
.y = 321 * t + 2
End With
Next
Type rect_type
x As Single
y As Single
End Type
Dim As rect_type rect1, rect2
'' Nested With blocks
With rect1
.x = 1
.y = 2
With rect2
.x = 3
.y = 4
End With
End With
Print rect1.x, rect1.y '' 1, 2
Print rect2.x, rect2.y '' 3, 4
x As Single
y As Single
End Type
Dim As rect_type rect1, rect2
'' Nested With blocks
With rect1
.x = 1
.y = 2
With rect2
.x = 3
.y = 4
End With
End With
Print rect1.x, rect1.y '' 1, 2
Print rect2.x, rect2.y '' 3, 4
Dialect Differences
- Not available in the -lang qb dialect unless referenced with the alias __With.
Differences from QB
- New to FreeBASIC
See also
