# waitForEx ## waitForEx DCli goes to great lengths to remove the need to use `Futures` and `await;`there are two key tools we use for this. `waitFor` and `streams`. `waitFor` is a fairly new Dart function which ONLY works for Dart CLI applications and can be found in the `dart:cli` package. The DCli API doesn't expose any futures despite using futures extensively in its internal workings. `waitFor` allows a Dart CLI application to turn what would normally be an async method (returning a future) into a normal synchronous method by effectively 'absorbing' a future. Normally in Dart, as soon as you have one async function, its async all of the way up. DCli simply wouldn't have been possible without `waitFor.` `waitFor` does however have a problem. If an exception gets thrown whilst in a `waitFor` call, then the stacktrace generated will be a microtask based stack trace. These stacktraces are useless as they don't show you where the original call came from. This is why `waitForEx` was born. `waitForEx` is my own little creation that does three things. 1. capture the current stack using StackTraceImpl 2. calls `waitFor` and catches any exceptions 3. If an exception is thrown it patches the stack trace captured in 1 and merges it with the interesting bits of the microtask exception. The result is that you get a clean stacktrace that points to the exact line that cause the problem and we have a stacktrace that actually shows where it was called from. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://dcli.onepub.dev/internal-workings/waitforex.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.