Method calls

A collected coin has work to hand off: count it, refresh the HUD, and play a sound. Each handoff is a method call.

The problem

PlayerController.CollectCoin calls four neighbors. The coin arrives as a parameter, the score and HUD are class fields, and audio is optional. Each call needs the correct object and arguments at the correct position in the execution chain.

When to reach for it

Use a call when another method already owns the behavior you need. Pick call to invoke it. Pick method group when you need the method itself as a delegate value, with no parentheses or argument list.

The context sensitive checkbox starts on. The menu then offers methods the open type can already call: its own methods, inherited methods, and statics already available to the file. Turn it off to browse the hierarchical project palette by namespace and type. An instance method found there starts with an empty target pin because Round Trip will not guess which object should receive it.

See it

Figure 1. The call chain in PlayerController.CollectCoin.

Figure 2. Right-click the canvas and the action menu opens where you clicked. The search field is focused and the list is context sensitive.

Do it

1. Open a method graph and right-click an empty part of the canvas. The action menu opens at the click.
2. Search under call. Expand the inherited or static group when that is where the method lives. Turn off context sensitive only when the scoped list does not contain the method.
3. Choose an overload. The selected overload decides which argument pins appear.
4. For an instance call, connect the object to the target pin. Calls on the current object already carry their implicit target. You can also drag the object’s output pin onto empty canvas: its member menu offers the type’s methods with a call action, and typing in its filter lists the type’s own matches before nested ones.
5. Connect or type each argument. A generic method asks you to choose each type argument before the call is created.
6. Put an impure call on the exec chain. Pure calls produce data without exec pins.
7. Press Compile in the toolbar. The call is inserted at its execution-flow position and the file is parsed back into the graph.

You should see

The call card has a target when one is required, one pin per chosen parameter, and a result pin for a non-void return. Its header is bright teal #15B5A6 for this class or a superclass and dark teal #0B6E72 for another class, including a Unity or .NET method the call resolves to. Slate #566573, with ↗ after the title, marks external code: a call that resolves to no method in the project or anything it references.

A member read off a call’s result stays one pill. collision.GetContact(i).normal.y reads back as one GET pill, y with normal in its eyebrow, wired from the GetContact result, the same node you place by dragging that result pin. A constructor that starts with : this(...) or : base(...) shows that call as a node titled with the called type, with one input per argument, named and typed by the called constructor’s parameters.

Change one thing

In CollectCoin, compare coin.Collect() with _scoreCounter.AddCoins(...). Both are calls, but their targets come from different places. Follow each target wire back to its source.

What it writes

C#

What it writes

C#

coin.Collect();
_scoreCounter.AddCoins(CoinsPerPickup);
_hud.RefreshCoins(_scoreCounter.Coins, _scoreCounter.Score);
_audio?.PlayCoin();

When it goes wrong

When it goes wrong

Symptom	Check	Fix
Compile leaves the call pending	Look for an empty target, argument, or generic type slot.	Supply every required value, then Compile again.
The method is missing from the short list	Check whether context sensitive is enabled.	Turn it off and browse the namespace and type hierarchy.
Method group is disabled	Check whether the method is generic.	Use a non-generic method group or finish the edit in C#.

Next

• Get and set
• Operators and expressions
• Preview and Compile