use bigint; is lexically scoped. You can limit what it effects by putting curlies around it.

no bigint; cancels bigint's effects. It is also lexically scoped.

Another way of limiting bigint's effect — turning numerical constants into Math::BigInt objects — is to avoid using bigint completely and create Math::BigInt objects for the appropriate constants manually.

For example, say you're starting with the following:

>perl -MO=Concise,-exec -Mbigint -e"my $big = 1234; for (1..4) { foo($
+big) }"
...
7  <0> pushmark s
8  <$> const[RV \HASH] s        <-- for loop indexes are needlessly
9  <$> const[RV \HASH] s        <--   BigInt objects.
a  <#> gv[*_] s
b  <{> enteriter(next->h last->k redo->c) lKS/8
...
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Let's selectively make $big a BigInt to avoid making the loop indexes objects:

>perl -MO=Concise,-exec -MMath::BigInt -e"my $big = Math::BigInt->new(
+'1234'); for (1..4) { foo($big) }"
...
b  <0> pushmark s
c  <$> const[IV 1] s            <-- Much better
d  <$> const[IV 4] s            <--
e  <#> gv[*_] s
f  <{> enteriter(next->l last->o redo->g) lKS/8
...
[download]