Difference between revisions of "With"
From Lazarus wiki
Jump to navigationJump to searchm (Added back page link) |
(Undo revision 133977 by Trev (talk): a “back to <some static page>” does not make sense, as there are many pages referring here) Tag: Undo |
||
Line 1: | Line 1: | ||
− | {{ | + | {{With}} |
− | |||
− | |||
− | |||
− | |||
The [[Reserved word|reserved word]] <syntaxhighlight lang="pascal" enclose="none">with</syntaxhighlight> allows overriding the scope lookup routing for named scopes for the duration of one [[statement]]. | The [[Reserved word|reserved word]] <syntaxhighlight lang="pascal" enclose="none">with</syntaxhighlight> allows overriding the scope lookup routing for named scopes for the duration of one [[statement]]. | ||
− | == | + | == routing == |
− | |||
[[Identifier]]s are searched in the following order, until there is a hit: | [[Identifier]]s are searched in the following order, until there is a hit: | ||
− | |||
# current [[Block|block]] | # current [[Block|block]] | ||
# enclosing block, if any | # enclosing block, if any | ||
Line 21: | Line 15: | ||
# the [[System unit|system unit]] (unless implicit inclusion has been disabled) | # the [[System unit|system unit]] (unless implicit inclusion has been disabled) | ||
− | == | + | == override == |
− | + | The lookup order can be temporarily overridden with a <syntaxhighlight lang="pascal" enclose="none">with</syntaxhighlight>-clause. | |
− | The lookup order can be temporarily overridden with a <syntaxhighlight lang="pascal" enclose="none">with</syntaxhighlight>-clause. It looks like this: | + | It looks like this: |
− | |||
<syntaxhighlight lang="pascal"> | <syntaxhighlight lang="pascal"> | ||
with namedScope do | with namedScope do | ||
Line 31: | Line 24: | ||
end; | end; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
− | |||
This puts <syntaxhighlight lang="pascal" enclose="none">namedScope</syntaxhighlight> at the top of the routing. | This puts <syntaxhighlight lang="pascal" enclose="none">namedScope</syntaxhighlight> at the top of the routing. | ||
Identifiers are looked up in <syntaxhighlight lang="pascal" enclose="none">namedScope</syntaxhighlight> first, before other scopes are considered. | Identifiers are looked up in <syntaxhighlight lang="pascal" enclose="none">namedScope</syntaxhighlight> first, before other scopes are considered. | ||
Line 61: | Line 53: | ||
In practice this will always be a compound statement, though. | In practice this will always be a compound statement, though. | ||
− | == | + | == see also == |
− | |||
* [[Namespaces|namespaces]] | * [[Namespaces|namespaces]] |
Revision as of 23:46, 27 August 2020
The reserved word with
allows overriding the scope lookup routing for named scopes for the duration of one statement.
routing
Identifiers are searched in the following order, until there is a hit:
- current block
- enclosing block, if any
- the block enclosing the enclosing block, if any
- … (and so on)
- the most recently imported module, that means for instance the unit that appears at the end of the
uses
-clause list, if any - the penultimate module that has been imported, if any
- … (and so on)
- the first imported module, that means for instance the first unit appearing in a
uses
-clause, if any - the system unit (unless implicit inclusion has been disabled)
override
The lookup order can be temporarily overridden with a with
-clause.
It looks like this:
with namedScope do
begin
…
end;
This puts namedScope
at the top of the routing.
Identifiers are looked up in namedScope
first, before other scopes are considered.
namedScope
may be
- the name of a
unit
that has previously been imported via auses
-clause in the current section - the name of a structured variable, that could have named members, i. e.
If multiple with
-clauses ought to be nested, there is the short notation:
with snakeOil, sharpTools do
begin
…
end;
which is equivalent to:
with snakeOil do
begin
with sharpTools do
begin
…
end;
end;
Note, begin
-end
are not part of the syntax, but with
… do
has to be followed by exactly one statement.
In practice this will always be a compound statement, though.