Your question makes a limiting assumption. Let's take a step back here. Why not just
bool ParametersValid (or
Boolean parametersValid)? It's perfectly sufficient in my opinion.
isThat remind me of that anecdotal secretary who files everything under "T" ("the rent", "the invoices" etc.) :)
If the need for such prefixes becomes acute (it's not immediately obvious what
parametersValid stands for), it may indicate the object design is simply bad.
Using prefixes is Hungarian notation of sorts and in this context, it's poor man's substitute of proper refactoring and splitting the class.
OP's question is about the particular isFoo style of naming boolean
methods which is conventional in a number of languages
Maybe, but the question is not tagged with the name of any particular programming language, so I treat it as language-agnostic.
suggesting a different convention is not useful.
I'm not really suggesting a different convention, I'm rather saying that one does not need to follow any strict convention in this aspect, other than common sense and clear naming in general.
The idea that some strict convention is required is what created the OP's problem in first place.
If he adopts my point of view, his problem goes away, hence my answer is (potentially, of course - like any other answer) useful.
I opt for simplicity. See
BackgroundWorker class in .NET. It has a
CancellationPending property - not
HasBeenCancelled etc. Just keep it simple!
Furthermore, the convention you suggest is ambiguous by your own admission ("...it's not immediately obvious...")
I wrote it conditionally, you took it out of context. If it's not immediately obvious ... implies the class is too big, which is a problem in its own right.
Finally, the is in isFoo should be read as a verb; this use of prefixes is distinct from any Hungarian notation and in any case it's not necessarily indicative of poor design.
Verb or not verb, it's only reflecting the fact that the return type is boolean, which is redundant.
That's why I said it's Hungarian notation of sorts.