CODEWITHSUNDEEP
variablesvb6variantstrict
Maestro
Maestro

Reputation: 9508

VB6: Disable variants

I have a large VB6 projects where a lot of variables don't have an explicitly defined type, so they automaticly default to Variant type. Finding all those by hand is a massive task, so is there any way to automate this? In VB.Net it's possible to disable all automatic use of variants using 'Option Strict', but VB6 doesn't have that option.

Right now I added DefByte A-Z to every class, which makes the default type 'Byte' instead of 'Variant'. This let me catch a lot of undefined variables at run-time, as soon as they are assigned a value larger than 255. But it's still not fully fool-proof.

Is there a more reliable way to detect all undefined variables?

Upvotes: 7

Views: 735

Answers (4)

tcarvin
tcarvin

Reputation: 10855

Use an programmer's text editor (I use UltraEdit) and do a mass search across you project source directories.

Start with searching for Variant (obviously), though you probably already did that.

Next use a regular expression type search for something along the lines of:

 *Dim [a-zA-Z][a-zA-Z0-9_]*\p

That should get the Dim x scenario without the trailing As DataType.

Use *Dim [a-zA-Z][a-zA-Z0-9_]*,.* to find the Dim a, b, c As Integer type of scenarios.

Use *Dim .*, [a-zA-Z][a-zA-Z0-9_]*,.* for odd ball scenarios like Dim a As Integer, b, c As Long

Repeat the above seaches with Private and Global instead of Dim and that should get just about everything.

Upvotes: 2

qxn
qxn

Reputation: 17584

Decorate your modules with Option Explicit.

This phrase should go at the top of each module you create. When done so, it will cause a compiler error when undeclared variables are encountered.

Option Explicit will not, however, prevent type-less variable declarations, such as

Dim i

The variable i will be declared as a variant, and no compiler error will be thrown even with Option Explicit defined.

Upvotes: 4

MartW
MartW

Reputation: 12538

I used to use Aivosto's Project Analyzer to pick up things like this. There's a demo version which will give you a good idea what it can do.

Upvotes: 5

Bob Mc
Bob Mc

Reputation: 2008

I don't think there's a "foolproof" way to detect all undefined variables. However, the Option Explicit statement will require that all variables be declared in the module in which the statement appears, so the compiler will flag any instances where that is not the case. There is also an IDE option that automatically adds this statement to the start of any new module.

Upvotes: 2

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