Databases
StackOverflow2013
Postsdbo
POBehaviour of exceptions within delegates in C# 2 hosted by MS Excel and COM
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POBehaviour of exceptions within delegates in C# 2 hosted by MS Excel and COM
    primarykey
    data
    text
    <p>Morning all,</p> <p>Bit of a language theory question here... I've found some references online suggesting that exception handling and delegates in C# have some different behaviour in some cases but I cannot find any concrete documentation on the matter.</p> <p>We recently had some big problems with exceptions inside delegates for a Microsoft Excel addin causing a hard-crash in the MSVC runtime. Removing delegates solved this but I'm now curious to find out the gory details.</p> <p>As a terse example of the core code:</p> <pre><code>Delegate del; // initialized elsewhere try { del.DynamicInvoke(); } catch(Exception e) { /* Parsing of exception to generate user-friendly message here */ } </code></pre> <p>The above construct allowed a centralized form of error handling and from a pure code point of view was clean and concise. Each publicly exposed function was declared as a delegate and executed via the above fragment.</p> <p>In a simple console app, throwing an exception from the delegate or just a plain unexpected error (e.g. "accidentally" calling ToString() on a null pointer) works as expected and the error is handled as desired.</p> <p>Throw in MS Excel and you get hard-crashes. Stepping through the code will show where the error occurs but <em>no</em> stack unwinding appears to take place before everything comes down in a big fireball of destruction.</p> <p>My hypothesis is that COM, hosting the .NET runtime (and hence our code) is doing something different to normal .NET code execution. This kills the end-point and Excel doesn't know this, which in turn tries to access the end-point via COM only to find it has somehow disappeared and Excel craps out in return.</p> <p>This only happens with the combination of Excel+COM+delegates, but I don't honestly know which is the more influential in this behaviour... any thoughts?</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USJoel Coehoorn
    1. USuser25519
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POBehaviour of exceptions within delegates in C# 2 hosted by MS Excel and COM
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POBehaviour of exceptions within delegates in C# 2 hosted by MS Excel and COM
      1. USRob
      1. VTFavorite
    3. VO
      singulars
      1. POBehaviour of exceptions within delegates in C# 2 hosted by MS Excel and COM
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload