DouKaku?

#include <string.h>

// なにもフォーマットしてない
int mysprintf(char *str, const char *format, ... ){
    strcpy(str, format);
    return strlen(str);
}

| printf |
printf := [:args |
    | formStrm valsStrm outStrm |
    formStrm := args first readStream.
    valsStrm := args allButFirst readStream.
    outStrm := String new writeStream.
    [formStrm atEnd] whileFalse: [
        | next width print scale format |
        outStrm nextPutAll: (formStrm upTo: $%).
        next := formStrm next.
        width := scale := 0.
        next ifNotNil: [
            next isDigit ifTrue: [
                formStrm back.
                width := Integer readFrom: formStrm.
                next := formStrm next].
            next = $. ifTrue: [
                scale := Integer readFrom: formStrm.
                next := formStrm next]].
        print := [:val |
            | str |
            str := val asString.
            width := width max: str size.
            outStrm nextPutAll: (str forceTo: width paddingStartWith: $ )].
        format := [:float |
            | str idx |
            str := (scale > 0 ifTrue: [float asScaledDecimal: scale] ifFalse: [float]) asString.
            (idx := str indexOf: $s) > 0 ifTrue: [str := str first: idx - 1].
            str].
        next caseOf: {
            [$%] -> [outStrm nextPut: $%].
            [$d] -> [print value: valsStrm next asInteger].
            [$f] -> [print value: (format value: valsStrm next asFloat)].
            [$o] -> [print value: (valsStrm next radix: 16)].
            [$x] -> [print value: (valsStrm next radix: 8)].
            [$c] -> [outStrm nextPut: valsStrm next asCharacter].
            [$s] -> [outStrm nextPutAll: valsStrm next asString]} otherwise: []].
    outStrm contents].

printf value: {'hoge %6.2f %6d %o %x %c %s %% fuga'. 1.234. 1234. 1234. 1234. 'a'. 'abc'}
"=> 'hoge   1.23   1234 4D2 2322 a abc % fuga' "