Avoid side effects when en exception has been thrown.

We don't want to check for exceptions after every single
line on our runtime methods. A better way to handle this
is to add the check in all methods that have direct side
effects (as e.g. writing to a property of the JS stack).

We also need to return whereever we throw an exception.
To simplify the code, ExecutionContext::throwXxx methods now
return a ReturnedValue (always undefined) for convenience.

Change-Id: Ide6c804f819c731a3f14c6c43121d08029c9fb90
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/particles/qquickv4particledata.cpp b/src/particles/qquickv4particledata.cpp
index 3cfce0ae90..0524a5a871 100644
--- a/src/particles/qquickv4particledata.cpp
+++ b/src/particles/qquickv4particledata.cpp
@@ -304,7 +304,7 @@ static QV4::ReturnedValue particleData_discard(QV4::SimpleCallContext *ctx)
     QV4::Scoped<QV4ParticleData> r(scope, ctx->callData->thisObject);
 
     if (!r || !r->datum)
-        ctx->throwError(QStringLiteral("Not a valid ParticleData object"));
+        return ctx->throwError(QStringLiteral("Not a valid ParticleData object"));
 
     r->datum->lifeSpan = 0; //Don't kill(), because it could still be in the middle of being created
     return QV4::Encode::undefined();
@@ -316,7 +316,7 @@ static QV4::ReturnedValue particleData_lifeLeft(QV4::SimpleCallContext *ctx)
     QV4::Scoped<QV4ParticleData> r(scope, ctx->callData->thisObject);
 
     if (!r || !r->datum)
-        ctx->throwError(QStringLiteral("Not a valid ParticleData object"));
+        return ctx->throwError(QStringLiteral("Not a valid ParticleData object"));
 
     return QV4::Encode(r->datum->lifeLeft());
 }
@@ -327,7 +327,7 @@ static QV4::ReturnedValue particleData_curSize(QV4::SimpleCallContext *ctx)
     QV4::Scoped<QV4ParticleData> r(scope, ctx->callData->thisObject);
 
     if (!r || !r->datum)
-        ctx->throwError(QStringLiteral("Not a valid ParticleData object"));
+        return ctx->throwError(QStringLiteral("Not a valid ParticleData object"));
 
     return QV4::Encode(r->datum->curSize());
 }