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Assert
The Assert function tests a condition and aborts the script if the condition tests false. This function mimics the common C and C++ ASSERT or assert macros.
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Assert( condition, message=nil ) |
condition is an expression that produces a result
(see Remarks).
message is optional, and is displayed if
condition fails.
The condition can be any condition that produces a value that can be tested. For example, if testing a numeric expression, the Assert will exit the script if the expression evaluates false, numeric zero, or nil. The table below lists the conditions that cause failure.
Assert Expression Failure Conditions
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Expression result: |
Failure condition: |
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number |
0 |
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string |
nil or 0-length |
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table |
nil (non existent) |
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boolean |
false |
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C pointer |
NULL |
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CFunction |
nil (non existent) |
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Lua thread |
nil |
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userdata |
nil (non existent) |
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nil |
always |
The following condition fails the Assert test and exits the script if fewer than 2 images were loaded.
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V = LoadImages(2) |
-- load 2 images and create a CImageView |
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Assert( V:Count() < 2 ) |
-- fails without a message if 2 images were not loaded |