c# - Throwing exceptions from Linq Query exception -

lets have input string need format list of keyvaluepair<string,float> entries. format of input string

key:value;key:value;... 

lets have linq code it

var orr = pco in (overrrides ?? string.empty).split(new char[] { ';' }, stringsplitoptions.removeemptyentries)           let pair = pco.split(new char[] { ':' }, stringsplitoptions.removeemptyentries)           select new keyvaluepair<string, float>(pair[0], float.parse(pair[1])); 

now, if input string not formated linq fail on 2 possible points, index out of range on pair[] , format exception on float.parse. both of these exceptions bobble , mean absolutely nothing caller.

i know have 2 workarounds (not use linq , loop 1990s or grab above exceptions , repackage), wondering if can somehow inject validation steps linq query throw own exceptions if detect anomaly (pair.length<2 or pair[1] not number)?

one simple option change to:

// don't think i'd use ?? this, that's not point of question. var unparsed = (overrrides ?? string.empty).split(new char[] { ';' },                                                    stringsplitoptions.removeemptyentries); var parsed = unparsed.select(x => parsepair(x));  ...  static keyvaluepair<string, float> parsepair(string text) {     // note more efficient using indexof/substring     string[] bits = text.split(new char[] { ':' }, stringsplitoptions.removeemptyentries);     if (bits.length != 2)     {         throw new argumentexception("value should colon-separated key/float pair");     }     float value;     if (!float.tryparse(bits[1], out value))     {         throw new argumentexception("cannot parse " + bits[1] + " float");     }     return new keyvaluepair<string, float>(bits[0], value); } 

you're still using linq "sequence" part - you're breaking "how handle single value" part separate method. (you could big statement lambda, wouldn't.) note doing so, test parsepair method independently.

(you might away .select(parsepair), depending on version of c# you're using. method group conversions , type inference aren't best of friends though.)