[PATCH] doc: Fix grammar errors in tutorial.md

[Lewis Chan]

Signed-off-by: Lewis Chan <bai...@gmail.com>
---
doc/tutorial.md | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/doc/tutorial.md b/doc/tutorial.md
index fdcc922d..a8ca911e 100644
--- a/doc/tutorial.md
+++ b/doc/tutorial.md
@@ -2155,7 +2155,7 @@ From this output, we have no way of knowing that the exception was thrown in `g(
```
#include <util/backtrace.hh>
seastar::future<> g() {
- return seastar::make_exception_future_with_backtrace<>(std::runtime_error("hello"));
+ return seastar::make_exception_future_with_backtrace<void>(std::runtime_error("hello"));
}
```
Now the output looks like
@@ -2376,7 +2376,7 @@ Consider the following asynchronous function `loop()`, which loops until some sh
```cpp
seastar::future<long> loop(int parallelism, bool& stop) {
return seastar::do_with(0L, [parallelism, &stop] (long& counter) {
- return seastar::parallel_for_each(std::views::iota(0u, parallelism),
+ return seastar::parallel_for_each(std::views::iota(0, parallelism),
[&stop, &counter] (unsigned c) {
return seastar::do_until([&stop] { return stop; }, [&counter] {
++counter;
@@ -2497,14 +2497,14 @@ In conjunction with seastar::app_template, initialization and cleanup look like
int main(int argc, char** argv) {
seastar::app_template app;
return app.run(argc, argv, [] {
- return seastar::async() {
+ return seastar::async([] {
std::cout << "Hello world\n";
my_class my_object;
// ... more code

// my_object will be destroyed here
return 0;
- });
+ }));
}
```

@@ -2519,7 +2519,7 @@ use of the seastar::defer() function to schedule an arbitrary cleanup function:
int main(int argc, char** argv) {
seastar::app_template app;
return app.run(argc, argv, [] {
- return seastar::async() {
+ return seastar::async([] {
std::cout << "Hello world\n";
my_class my_object;
// ... more code
@@ -2535,6 +2535,7 @@ int main(int argc, char** argv) {

// my_object will be destroyed here
return 0;
+ })
});
}
```
--
2.43.0

[Nadav Har'El]

On Tue, Dec 16, 2025 at 11:44 AM Lewis Chan <bai...@gmail.com> wrote:

Signed-off-by: Lewis Chan <bai...@gmail.com>
---
 doc/tutorial.md | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/doc/tutorial.md b/doc/tutorial.md
index fdcc922d..a8ca911e 100644
--- a/doc/tutorial.md
+++ b/doc/tutorial.md
@@ -2155,7 +2155,7 @@ From this output, we have no way of knowing that the exception was thrown in `g(
 ```
 #include <util/backtrace.hh>
 seastar::future<> g() {
-    return seastar::make_exception_future_with_backtrace<>(std::runtime_error("hello"));
+    return seastar::make_exception_future_with_backtrace<void>(std::runtime_error("hello"));

We use make_exception_future<> in a bazillion places and it works just fine, no need to write make_exception_future<void>.

Is make_exception_future_with_backtrace<> really an error? Maybe it should be fixed in that template, not in the documentation?

 

 }
 ```

 Now the output looks like
@@ -2376,7 +2376,7 @@ Consider the following asynchronous function `loop()`, which loops until some sh
 ```cpp
 seastar::future<long> loop(int parallelism, bool& stop) {
     return seastar::do_with(0L, [parallelism, &stop] (long& counter) {
-        return seastar::parallel_for_each(std::views::iota(0u, parallelism),
+        return seastar::parallel_for_each(std::views::iota(0, parallelism),

What's wrong with 0u? It's been part of C++ since around 30 years.

 

             [&stop, &counter]  (unsigned c) {
                 return seastar::do_until([&stop] { return stop; }, [&counter] {
                     ++counter;
@@ -2497,14 +2497,14 @@ In conjunction with seastar::app_template, initialization and cleanup look like
 int main(int argc, char** argv) {
     seastar::app_template app;
     return app.run(argc, argv, [] {
-        return seastar::async() {
+        return seastar::async([] {

Yes, this definitely looks like a syntax error.

 

             std::cout << "Hello world\n";
             my_class my_object;
             // ... more code

             // my_object will be destroyed here
             return 0;
-    });
+    }));
 }
 ```

@@ -2519,7 +2519,7 @@ use of the seastar::defer() function to schedule an arbitrary cleanup function:
 int main(int argc, char** argv) {
     seastar::app_template app;
     return app.run(argc, argv, [] {
-        return seastar::async() {
+        return seastar::async([] {
             std::cout << "Hello world\n";
             my_class my_object;
             // ... more code
@@ -2535,6 +2535,7 @@ int main(int argc, char** argv) {

             // my_object will be destroyed here
             return 0;
+        })
     });
 }
 ```
--
2.43.0

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[Łukasz Kurowski]

> Is make_exception_future_with_backtrace<> really an error? Maybe it should be fixed in that template, not in the documentation?

I checked and it actually is

To view this discussion visit https://groups.google.com/d/msgid/seastar-dev/CANEVyjsBOfhxWTWk5qkdRacNEAac22GJjQ_nt6Rf9CY7hGOSdg%40mail.gmail.com.

[Chan Lewis]

Nadav Har'El <n...@scylladb.com> 于2025年12月16日周二 17:50写道：

On Tue, Dec 16, 2025 at 11:44 AM Lewis Chan <bai...@gmail.com> wrote:

Signed-off-by: Lewis Chan <bai...@gmail.com>
---
 doc/tutorial.md | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/doc/tutorial.md b/doc/tutorial.md
index fdcc922d..a8ca911e 100644
--- a/doc/tutorial.md
+++ b/doc/tutorial.md
@@ -2155,7 +2155,7 @@ From this output, we have no way of knowing that the exception was thrown in `g(
 ```
 #include <util/backtrace.hh>
 seastar::future<> g() {
-    return seastar::make_exception_future_with_backtrace<>(std::runtime_error("hello"));
+    return seastar::make_exception_future_with_backtrace<void>(std::runtime_error("hello"));

We use make_exception_future<> in a bazillion places and it works just fine, no need to write make_exception_future<void>.

Is make_exception_future_with_backtrace<> really an error? Maybe it should be fixed in that template, not in the documentation?

Yes, it does throw errors. I check the code and find that make_exception_future_with_backtrace doesn't have a default T value like make_exception_future<>. I think we may need to give T a default void ?

 

 

 }
 ```
 Now the output looks like
@@ -2376,7 +2376,7 @@ Consider the following asynchronous function `loop()`, which loops until some sh
 ```cpp
 seastar::future<long> loop(int parallelism, bool& stop) {
     return seastar::do_with(0L, [parallelism, &stop] (long& counter) {
-        return seastar::parallel_for_each(std::views::iota(0u, parallelism),
+        return seastar::parallel_for_each(std::views::iota(0, parallelism),

What's wrong with 0u? It's been part of C++ since around 30 years.

parallelism has an int type, and doesn't match. So the compiler complains. remove 'u' to avoid implicit conversion

[Chan Lewis]

Hi. This is my first time submiting a patch for seastar project. I only use git send-mail to generate this patch. I haven't created an issue or PR on the repo side. Is this the right way to do it ?

Chan Lewis <bai...@gmail.com> 于2025年12月16日周二 18:26写道：