Why don't you put the whole assignment to eval? 
eval "$base\{$lastPart} = \$newData"

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But you can return a reference to the value to be able to change it: 

my $ref = eval "\\$base\{$lastPart}" || eval "$base = {}";
$$ref = $newData;

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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

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In reply to Re: How to get a reference from an eval() string? by choroba
in thread How to get a reference from an eval() string? by exilepanda

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