c# - How Can I Use IEnumerator.Reset()? -

how right way call ienumerator.reset?

the documentation says:

the reset method provided com interoperability. not need implemented; instead, implementer can throw notsupportedexception.

okay, mean i'm not supposed ever call it?

it's so tempting use exceptions flow control:

using (enumerator = getsomeexpensiveenumerator()) {     while (enumerator.movenext()) { ... }      try { enumerator.reset(); } //try inexpensive method     catch (notsupportedexception)     { enumerator = getsomeexpensiveenumerator(); } //fine, 1      while (enumerator.movenext()) { ... } } 

is how we're supposed use it? or not meant use managed code @ all?

never; mistake. correct way iterate sequence more once call .getenumerator() again - i.e. use foreach again. if data non-repeatable (or expensive repeat), buffer via .tolist() or similar.

it formal requirement in language spec iterator blocks throw exceptions method. such, cannot rely on working. ever.