How to use instanced struct values in a match statement?
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
82
add a comment |
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
82
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
add a comment |
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
82
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
82
asked Nov 23 '18 at 0:05
aethioaethio
82
asked Nov 23 '18 at 0:05
aethioaethio
82
asked Nov 23 '18 at 0:05
aethioaethio
82
asked Nov 23 '18 at 0:05
aethioaethio
82
82
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
add a comment |
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
add a comment |
1 Answer
1
active
oldest
votes
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
82
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
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1 Answer
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oldest
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1 Answer
1
active
oldest
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oldest
votes
active
oldest
votes
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
82
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
82
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
82
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
82
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
edited Nov 23 '18 at 1:36
aethio
82
edited Nov 23 '18 at 1:36
aethio
82
edited Nov 23 '18 at 1:36
aethio
82
82
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
45.1k694148
45.1k694148
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
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Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26