Constants | Godot GDScript Tutorial | Ep 03
Summary
TLDRThe video script explains the concept of constants in computer science, specifically within the context of GDScript used in game development. It details how to declare constants with the 'Const' keyword, emphasizing their immutability post-declaration. The script advocates for the use of constants over literals for better code readability, easier debugging, and efficient code maintenance. It illustrates the benefits with examples, such as changing game item speeds by modifying a single constant instead of numerous hardcoded values, and discusses the importance of naming conventions to visually distinguish constants from variables.
Takeaways
- 📝 Constants in computer science are values that do not change.
- 🔑 In GDScript, constants are declared with the keyword 'Const' followed by a unique name, an equal sign, and a value.
- 🈲️ Assigning an empty constant or a constant without a value is not allowed.
- 🔄 The difference between a variable and a constant is the keyword used; everything else is the same.
- 📊 Data types can be explicitly added to constants with a colon and data type name, but it's optional as the type is inferred.
- 🚫 Constants are read-only and cannot be modified after declaration and assignment.
- 👍 Using constants is beneficial for debugging, editing, and reading code.
- 💡 Beginners often use literals instead of constants, but constants improve code readability and maintainability.
- 🔍 Constants should be visually distinct from variables, often using uppercase letters for easy identification.
- 🔄 Changing a constant's value automatically propagates the change throughout the code where the constant is used.
- 🎮 Constants are ideal for values that will not change during the lifecycle of a game, such as player dimensions.
Q & A
What is a constant in computer science?
-In computer science, a constant is a value that does not change throughout the execution of a program.
How do you declare a constant in GDScript?
-In GDScript, constants are declared using the keyword 'const' followed by a unique name, an equal sign, and a value.
Is it possible to assign an empty value to a constant in GDScript?
-No, you cannot assign an empty constant; it must have an assigned value upon declaration.
What is the difference between a variable and a constant in GDScript?
-The only difference between a variable and a constant in GDScript is the keyword used for declaration; 'var' for variables and 'const' for constants.
Can you modify the value of a constant after it has been declared in GDScript?
-No, constants in GDScript are read-only after declaration, and modifications are not permitted.
Is it necessary to specify a data type when declaring a constant in GDScript?
-Specifying a data type when declaring a constant is not necessary as the data type is inferred from the assigned value, but you can explicitly add a data type for clarity.
Why should beginners avoid using literal values and instead use constants?
-Using constants instead of literals makes code more readable, easier to debug, and simplifies the process of editing code, especially when the same value is used in multiple places.
What is the advantage of using constants over literals in a large codebase?
-Using constants in a large codebase allows for easier maintenance and updating of values. Changing the value of a constant will propagate the change throughout the code where the constant is used, instead of having to find and replace every instance of the literal value.
What is the recommended naming convention for constants in GDScript to differentiate them from variables?
-A recommended naming convention for constants is to start their names with an uppercase letter, while variables start with a lowercase letter, making it visually clear which is which when reading the code.
Can you provide an example of how using constants can simplify changing a value in a large codebase?
-If a game's speed value is initially set as a literal 5 in multiple variables, changing it to 10 later would require finding and editing each instance of the literal 5. However, if the speed is declared as a constant, changing it to 10 would automatically update all instances where the constant is used, reducing the potential for errors and saving time.
Outlines
📝 Understanding Constants in GDScript
This paragraph explains the concept of constants in computer science, specifically within the context of GDScript used in Godot game engine development. Constants are fixed values that do not change throughout the program's execution. The declaration of a constant involves using the 'const' keyword, followed by a unique name, an equal sign, and a value. Assigning a value to a constant is mandatory, and attempting to change a constant's value post-declaration results in an error. The paragraph also touches on the importance of using constants over literals for better code readability, easier debugging, and maintenance. An example is provided where changing a game item's speed from 5 to 10 requires altering multiple lines of code when using literals, versus changing just one line when using a constant.
🔑 The Power of Constants in Code Efficiency
This paragraph emphasizes the benefits of using constants over hardcoded literal values in programming, particularly in game development. It illustrates how constants can significantly reduce the time and effort required for code changes. By using a constant for values that are unlikely to change, such as a player's height or width, any necessary adjustments can be made by simply altering one line of code, which then propagates throughout the entire codebase. The paragraph also discusses the importance of naming conventions for constants, suggesting that they should be visually distinct from variables to aid in code recognition and maintenance. Examples of such conventions include starting constants with uppercase letters, while variables begin with lowercase, although personal preference is acknowledged in choosing a convention.
Mindmap
Keywords
💡Constants
💡Declaration
💡Unique Name
💡Datatype
💡Literal
💡Read-Only
💡Debugging
💡Maintainability
💡Naming Convention
💡Hard-Coding
Highlights
A constant in computer science is a value that never changes.
In GD script, constants are declared with the keyword 'Const' followed by a unique name, an equal sign, and a value.
Assigning an empty constant is not allowed; a constant must have an assigned value.
The distinction between a variable and a constant is the keyword used; otherwise, the declaration is the same.
Data type can be explicitly added to a constant declaration for clarity.
The data type of a constant is inferred from the assigned value if not explicitly stated.
The format for declaring a constant includes the keyword 'Const', a unique name, optional data type, and an equal sign followed by a literal or data object.
Constants are read-only and cannot be modified after declaration and assignment.
Using constants can simplify debugging and code editing.
Constants should be used instead of literals for better code readability and easier debugging.
Hard-coding literal values can lead to more work when changes are needed across multiple lines of code.
Using constants can reduce the effort needed to propagate changes across a codebase.
Constants are recommended for values that will not change throughout the lifecycle of a game.
Naming conventions for constants should visually distinguish them from variables.
Using uppercase for constants and lowercase for variables can help in quickly identifying them in the code.
The choice of naming convention should be comfortable for the programmer and visually distinct.
Transcripts
so what exactly are constants in
computer science a constant is a value
that never changes so how exactly do you
declare a constant in GD script
constants are declared with the keyword
Const spelled Co n st followed by a
unique name an equal sign symbol and a
value all of these are required you
cannot assign an empty constant you
cannot have a constant without an
assigned value the only thing separating
a variable from a constant is the
keyword everything else is exactly the
same just like variables keep in mind
that each and every variable in constant
you declare must have a unique name or
an error will be thrown
now just like variables you may also add
a datatype explicitly by adding a colon
science symbol followed by the data type
in this case we have declared a constant
called value never changes and assigned
it the datatype integer which is
assigned a literal integer 1 assigning a
datatype to a constant is not necessary
as the datatype is inferred to the
constant with the assigned value
basically a constant declaration format
looks like the following you have the
keyword Const followed by a unique name
for the constant with the option to a
data type but this must be followed by
an equal sign symbol followed by a
literal or data object everything in
yellow is required while everything in
white and the parentheses is optional
one thing to note is that constants are
read only after declaration therefore
modifications are not permitted after
Declaration and assignment let's take a
look at a quick example we declared a
constant value never changes and
assigned it the literal integer 1
somewhere in the code after the
declaration if we try to assign a new
value to our constant value never
changes in this case we're trying to
assign it the value 100 this will throw
an error in GDD script there are pros
when using constants
one thing I noticed with beginners is
the use of literal values beginners tend
to use literal values instead of
assigning literal values to constants I
recommend using constants because you'll
have an easier time debugging you'll
save time when editing code and of
course easier time reading code one
thing I noticed with beginners is this
question aren't constants the same as
literals and yes you can use literals
instead of constants to the compiler it
doesn't make a difference how values are
given however for the sake of readable
code and easier debugging you should use
constants let's take a look at some
examples so to a beginner let's say that
they have a speed for their game items
and in this case they need to use an
integer value of 5 what a beginner
typically does is they just hard inject
literal values in this case you can see
we have three variables a player speed a
laser speed and a boomerang speed all
being assigned the literal integer 5 now
let's say we need to change our main
speed for the game to be 10 instead of 5
now we've gone ahead and changed the
speed to 10 in our case to change our
main speed for game items we needed to
manually find and edit three lines of
code now this doesn't seem to be a lot
of work for three lines of code however
if we had more code this would take more
time in this case we have 20 variables
that rely on the speed value 10 as you
can see we have 20 lines of code now
imagine if we had to change 20 lines of
code when we decided that the speed is
too fast you're in trouble now because
you need to change 20 lines of code that
means you need to take the time to
manually find in your script any code
that uses your speed and you have to
find them all and if you fail to find
them all if you even forget about one
line of code that uses the old value
speed 10
your game may perform as it's not
intended to perform because you forgot
one line of code let's go ahead and fix
this instead of hard-coding the speed
for the game as a literal value instead
we will assign that value to a constant
and
case we have a constant speed which is
equal to five five being the value for
our speed in our game now that we have
our constant called speed which holds
our speed for the game in this case five
we can go ahead and work on our game as
time passes by maybe we have a thousand
line of code that rely on our constant
speed as you can see here we have
changed one line of code we have changed
the speed from five to ten and now this
change in our value to our constant
speed will propagate to the rest of our
code as you can see here we have
essentially edited a thousand line of
code by just changing one line of code
as you can see here this is the power of
using constants instead of injecting
literal values I recommend using
constants when you want to declare a
value that you know will never change in
the life cycle of your game for example
you may have a player and that player
may have a height and a width instead of
injecting the raw literal value all over
your code assign that value to a
constant and then assign that constant
to your code in this case this is good
practice because the player height and
player width will most likely never
change throughout the game lifecycle and
if you do happen to want to change the
value all you have to do is change one
line of code and it propagates to the
rest of your code one thing to keep in
mind is the naming convention when using
constants make sure that naming
conventions for constants are visually
different than variables this is
recommended to help you as a programmer
recognize what is a constant versus what
is a variable when looking through your
code let's take a look notice how all my
constants start with an uppercase just
so that I can visually know that when I
read anything with an uppercase in its
name that it is a constant and that I
intend to never change its value now
this is different than how I declare my
variables as you notice I declare my
variables starting in lowercase this is
so when I see anything starting with
lowercase I know that the value can
change another example
of a constant being visually different
than a variable as some people tend to
use uppercase to name their constants
while using whatever they want with
their variables again you don't have to
use this
they are visually different use whatever
you are comfortable with again just make
sure the to help you as a programmer
that the constant is visually different
than the variable
استعرض المزيد من الفيديوهات ذات الصلة
5.0 / 5 (0 votes)